Vael
Legend
I feel like that doesn't capture my goals. I am looking to be able to offer play that is not all-alpha-all-the-time. So I want diversity. I'd like to be able to sometimes offer conserve-your-power-carefully play.
So it is about diversity in play, not punishing players.
I feel like you can get there with varying up encounter design and rewards.
Don't have all the monsters on the map or grid at once. Maybe put half of the monsters just out of sight around the corner. If they nova the first group, more come in after.
Second, consider that there are quite a few spells that have a duration of 10 minutes to an hour. Let PCs have multiple fights before these spells give out. And if the party doesn't have them, give them as rewards.
As you sip from the enchanted pool, the magic fades from the water. You are under the effect of the Dragon's Breath Spell, but don't have to concentrate. Or the Bless Spell, and it'll last for the next hour.
Side Note: A lot of concentration buffs only last 1 minute. Extending some of them to 10 or 30 minutes would be another way to incentivize a party to have multiple combat encounters. I know, it leads to long pre-battle buffing routines, but Concentration does limit that.