Same, I was averaging 5~10 fights per long rest by the end of the game because I was trying to efficiently swap people out depending on who was low on health or spells, or use whoever I thought would have the most relevant dialogue for the quest(s).

My default roster was usually either Shadowheart, Gale and Laezel or Karlach, Wyll and Astarion. I was playing an archer sniper ranger so I basically always had two melee, one caster blaster and me as DPS and CC through arrows. I actually really liked the arrow system to give bow users more utility and if I ever run a campaign I'd like to adopt that. I'd make them cheaper though.

I never got to actually use Halsin. I tried to swap him in several times and it just never worked, then he was killed via plot events in act 3 via a mechanism where I could not save him. I used Jaheira a bit in late act 3, just for the Harper & Minsc stuff, not much after that. Never used Minsc, too much overlap with me, Laezel and Karlach.

I found both Wyll and Gale pretty frustrating, but that's likely because I was trying to be so conservative on rests.

Don't know how people have already run through 3+ times, I spent like 150 hours on my first run and saw probably 85% of the game... also the ending was pretty disappointing. I'm not itching to dive back in but I'd be interested in DUrge as well as interacting with Minthara more.