Herein is the problem (for me). My group gets together twice a month, if we're lucky. We get about 3 hours of "quality" time each session (after taking out breaks, snacks, general socializing, etc.) Knowing that the majority of our time is going to be spent with "another ho-hum goblin encounter that will only challenge us by spending a 1st level spell and a few arrows" or a trap that might do 1-6 hp of damage, it just doesn't seem a good way to spend time.
Any one else experiencing this? Any work-arounds?
Yes. I've been experiencing this since I first started playing D&D, though I didn't realize it was actually a problem until I played other games and then went back to play D&D again when 3e dropped.
There is no single answer to this problem - when we run games with these kinds of limits we're basically trying to cram the round D&D peg into the square "3-4 hour time limit" hole. D&D just isn't built to be played this way - it's designed to be a resource attrition game and getting around that aspect of it lead to turning the game into something else - something that may or may not mesh well with the ideal version of D&D that your players have in their heads.
Some options are:
* Throw out the trivial combat encounters. Just remove them from the game. If you only have 3-4 hours to play and your group savors the tabletop combat game then every single combat you present should be a major event. In 5e terms, never give the players less than a Medium encounter difficulty and lean towards the Hard and Deadly ones. You can also string two Medium encounters together back-to-back to create the equivalent of a deadly encounter that is less deadly but can save you some time because you don't have to go through the "overhead" steps twice (i.e. map drawing, initiative rolls, etc.)
PROS: Every combat is exciting because every combat "matters", with only 3 hours of play time at least you know there will be one big event that grabs everyone's interest and holds their attention.
CONS: Every combat will be more deadly than average - I actually don't recommend doing this until you hit 5th level in 5e because you're likely to just slaughter your PCs. The Encounter math in 5e is just not great, so you have to design encounters by "feel", which means that you can easily misjudge how difficult you've made the encounter (either too easy or impossible are both concerning). The "feel" of your game will trend to high heroism - if your PCs are always facing difficult odds and winning it's impossible to run a "gritty" game (or at least it is for me - YMMV, and this may not be a "con" if that's the kind of game you want to run). You can't use published campaign adventures "as is" - you'll have to modify almost every encounter. You will likely want to have a short rest after every encounter and a long rest after 3-4 encounters instead of 6-8 (mostly because you're expecting your PCs to do twice as much work in each encounter, so they're going to need to rest after every one instead of after every-other one).
* Run trivial encounters in "Theater of the Mind" style. You can cut down on overhead even more if you're willing to run trivial encounters differently than standard ones. Don't draw a map and break out the minis, instead just run it descriptively. Use side based initiative and have the players go in decreasing initiative bonus order by default - so you have a fixed order and can get things going right from the start - but let them arrange their own actions to taste among themselves, then have the monsters go. Fixed order of action in combat can speed things up amazingly - a thing that I tend to forget when I'm away from non d20-based games for a while.
PROS: "Trivial" encounters are truly trivial in this system but still eat up the minimal resources they're supposed to. Published adventures can be used as is as long as you take the minimal effort to decide beforehand which encounters are trivial and which are not. With practice and buy-in from your players you can make these kinds of trivial encounters run in 5-10 minutes, saving more time for role playing interactions and the set piece encounters that are more exciting.
CONS: Some players balk at using two different sets of rules for combat - identifying some encounters as trivial and others as important strikes some players as an overt game mechanic making its way into their narrative. For others it's the reverse - it's an overt narrative structure worming it's way into their game. Regardless of the objection, they may not like it and prefer consistently boring combats over inconsistent mechanics. You have to figure out how to adjudicate combat theater of the mind style when the game rules all use hard distances and adjacency rules for things like opportunity attacks and then make sure you apply these rules consistently. As with the first option above, this can also make your game tend towards the "high heroic" because your PCs will be consistently wiping the floor with groups of mooks in very short combats.
* Instead of dropping trivial combats entirely or running them under different rules, merge multiple trivial combats together into one larger combat. You can't always get away with this, but like stringing two Medium combats together into one Deadly one, you can also string together 2-3 Easy combats to make one Medium or Hard one, or an Easy and a Medium one together to make a Hard one.
PROS: If you're using published adventures, this is often easier than it sounds - especially among older ones there are often clusters of rooms stocked with mook-level monsters (like goblins and orcs) that you may already be running like this anyway - just cast your gaze a little wider to look for other opportunities. If you're building your own adventures you can set your encounters up to come in waves like this from the get-go.
CONS: The same cons as the first option, only less so - there's less worry that you'll just outright slaughter your PCs, but the Encounter math in 5e makes it easy to make an encounter either more or less overwhelming than you intended it to be - especially after level 5 or so. You can't always make this work, and even if you could your combats would start to feel very "samey" as the players will be expecting you to pull the "wave of enemies" card over and over again.
* Reskin your trivial encounters to make them more interesting conceptually if not tactically. Take the stats that you have and make them something else that fits the theme of the adventure but isn't just "more orcs". For example, an orc warband in a demon-touched dungeon might become a pack of "rage demons" wandering the levels looking for victims to slaughter, in a haunted forest a group of ghouls might be reskinned as a pack of "ghoulish wolves", an ooze might be reimagined as a living spell that has physically manifested and is now absorbing whatever living things it can touch, etc. At least the players get the enjoyment of fighting something they've never fought before, even if the block of stats are numbers they've defeated hundreds of times.
PROS: Only limited by your imagination - a block of stats can become anything. Just describe the creature differently and you may even start having it behave differently tactically. Even if it is the same "trivial" combat it can feel more exciting if everyone thinks they're fighting something different. Easy to judge whether it's "balanced" or not because you know the players have fought this bag of stats multiple times and know how it went.
CONS: You know it's the same skeleton stats, even if you're describing it to the players as an army of clockwork constructs built by the Mad Artificer of Ludd - you may not get the same fun out of playing the same block of stats that the players might get from fighting it because of that knowledge (especially true if lightning doesn't strike and you can't figure out how to make it behave tactically different from the source creature). If your players find out what you're doing it may break the illusion - this trick relies on novelty, and if they figure out that the novelty is just a veneer, they may not get the excitement out of it. It's not easy to do this sort of thing with published adventures, unless you want to retheme the whole adventure (which I've done - it can be fun, but it's a lot of work). You are limited by your imagination, and if inspiration doesn't strike then you might not be able to come up with something more interesting that what you've already got.
Those are a few ideas I've used over the years. There's also some merit in the idea that some folks are suggesting that it might be time to look for a different game system - in my regular group we're using 13th Age which is still a d20-descendant, but has an explicit "high heroic" feel to it and so trivial encounters are discouraged and all of our combats are exciting ones (in fact I build all of my encounters to be what 5e would call "Deadly" - we typically play once per month for 4 hours and have 1-2 combats per session, so I know your pain).
