This is a very trad-/beg/ statement, and maybe I just somehow missed this, but with acrylics, using a larger brush than you may think you need allows you to use unthinned paints.

Writing this embarrassing statement in case it helps others, because nowhere did I see anyone mention this. It was only recommended due to some philosophical "it helps you loosen up" mumbo jumbo or the tangible benefit of size/stroke variation. I was misled by my own reasoning that "I am making small works, without much variation. I should use small brushes then."

I was so fucking confused why I was getting roping (paint squishing out the edges) unless I thinned this shit down to the point even opaque colors were being translucent.