My thoughts:
First off, thank you for taking the effort to DM this little expedition. DMing can be fun but its always work as well, so I commend the effort.
In general I agree with your assessments, a few of my own:
- I think the combination of both the encounters AND the time pressure was the key on my character. This both consumed my resources and ensured that I could not make heavy use of my rituals....though I did slip a few in.
- In general I do agree that everyone had their bright spots this game, and I think all the players would have felt "cool" at one point or another. I think the Bard may be the MVP....those bardic inspirations were gold this game.
- Your right that in this scenario I felt a lot of pressure on my spells, both in slots and spells prepared. In hindsight I would have made a few spell adjustments, for example, having banishment and evards was a bit overkill.
- First time I've seen the new rogue AIM action. I'm not sure if I like the rogue being able to just have advantage all the time for such a trivial cost, feels like it takes a little something away from the game. That said, I agree the rogue and fighter both had their moments.
- Counterspell as a DM has always been a personal pet peeve of mine. I honestly hate shutting down the fun of my players in such a "slap your face" kind of manner. Now having faced it as a player.... I really just hate that spell so much, so anti-fun. Obviously a personal belief that not everyone will agree with.
- So I am used to larger groups, and I will say the biggest thing I learned this game was just how incredibly oppressive Legendary Resistances can feel to a caster. When we fought the demon, I had assumed it had 3 resistances. In my groups when you have like 3 spellcasters, burning 1 spell to blow through his defenses (assuming everyone does it) is not TOO bad. But when you feel like it may literally be you or one other caster, and you have to consider blowing 2 or even 3 spells.... that is just incredibly daunting.
- Thank you for helping me apparently air out dozens of years of dice karma
I was telling my entire group about it, I can't believe how cold my dice were at the beginning. But it looks like things balanced out, I had some really good damage rolls toward the end.
So to the question that started this all. Are Casters or Martials OP in anyway? So for groups that play heavily or exclusively in this kinds of scenarios (which granted is the WOTC baseline), than I think there is good balance there. Fighters can just go nuts fight after fight. Casters have to be little accountants....but you get rewarded for that big moment when the monster goes pop and you feel like a million bucks. At no point did I feel dominant or worthless, just varied from encounter to encounter.
Ultimately though, in my experience many campaigns are not exclusively these kind of days. There are 1 encounter kind of days, and there are downtime segments where time is not really a factor. In those scenarios?....I think casters still come off looking pretty darn good in terms of both power and flexibility.
So I think what this shows is that if you play the WOTC baseline....there is very nice balance between the classes, and all classes contribute in different but useful ways. And that pressure can be fun for a caster, who has to really make key decisions on what to cast when.
So there we go.... and now the debates can continue to rage
There are levers there to pull to change that, and so many DMs are stubbornly reluctant to do it for some reason.
The simple reason.... is that the levers are as much narrative ones as mechanical ones. Sometimes your party is exploring a place and there isn't always a doom clock....its just an ancient place they found that they are going to check out. Sometimes you have a party scene, where it doesn't make sense to burn away lots of resources, and it would be expected to use your "big guns" if your going to use any at all.
Sometimes your players take on a great long journey, and it would feel weird to have 6 encounters in a single day....and then have no encounters the rest of the trip. And if you decide to make everyday a 6 encounter day....well just getting there could be your entire campaign.
So your right that doom clocks are very useful (and frankly at high level Dnd I consider them absolutely essential to have any real game session....otherwise the players are just going to win)....but lets also respect that utilizing them isn't "free", they do have narrative cost....and for many campaigns the story of why the encounters are happening is often more important than what the encounters are.