I'm with you, Mats. I develop full stack on a 16" MacBook Pro. I have as many screens (desktops) as I want, just 4-finger slide between them. Maybe it's not as fast as glancing to the side, but I think having my focus always being straight ahead maintains focus better than glancing to the side. I've tried using an iPad as a second screen, but it didn't seem like a prductivity boost.