I'm using two external 1440p displays at work and one 32" 4k at home (with a MBP). Mostly front-end development and music production at home.

Aerospace improved my productivity a lot on that front. My main apps/windows are now bound to an alt+key combination - I can easily switch without alt+tabbing like in the dark ages.

All my windows usually take up the full screen - I simply can't stand a window that doesn't fill the entire screen - not sure if that's some kind of OCD. The cognitive load of managing apps and spaces was quite high at the beginning, but now it's just muscle memory. I do recognize that it's not for everyone, but works very well for me.