Flamestrike
Legend
Barbarians effectively have perma-rage after round 1, with a bit of management, in every game I've GM'd or played.
Not on a default 6-8 encounter adventuring day they dont.
I've never seen a Barbarian, mine or someone else's, enter a major battle without Rage.
Thats because the games you play in dont make using player abilities a choice. They feature few enough encounters per adventuring day that all barbarians rage on round 1 of every battle, all paladins smite with every attack, all casters reach for their highest level spell on round 1 and so forth.
In my campaign, the default pacing is around 6 encounters per long rest. Our party barbarian is 7th level (Barb 5/ Fighter 2). He has 3 rages per long rest, meaning he only gets to rage for 50 percent of those encounters. Going into 'rage mode' is a meaningful player choice.
Same deal with our Ancients Paladin/ Moon Druid blowing a spell slot to smite, heal or cast a spell. He only has around 10 slots in total to stretch out over the whole AD. Choosing to use one is a meaningful choice, and not an automatic go to button.
I'm not that interested in nerfing Barbarians; I would rather bring Warlocks & Fighters up.
Its not a question of 'nerfing' anyone. A barbarian that is always in rage (by virtue of a shorter AD) is getting a massive leg up (as are full casters in such shorter ADs). Youre actually nerfing Warlocks, Monks and Fighters by default by dropping shorter ADs on the party.
I strongly suggest throwing the occasional longer AD at your party even if you stick to the 3-4 encounter pacing of your current campaign as default.
Another option is to insert race against time to [save the princess] or something. Design a ruin where the party [shortly after completing a long rest] are tasked with reaching the BBEG before the following midnight or [bad thing happens]. Stat up 12 medium-hard encounters and give the PCs 20 hours to complete it. They cannot long rest between the morning they wake and midnight of the next day as less than 24 hours has passed, however they can short rest as often as they want within those 20 hours.
They could conceivably short rest after every single encounter on the way to the BBEG. Your Warlock and Fighter will feel like Gods and your barbarian will have to marshal his rage and use it on only on the most challenging of the encoutners.
This is the strength of 5E. by simply messing with the rest allowances adn rest meta from adventure to adventure, you can grant different classes in your party a chance to own the spotlight.