Yup, starting to play 2+1 increased my 5+3 rating by 200 up to 1800 (lichess). But continuing to play 2+1 with no analysis or thought hasn't increased my rating further.

I do only play for fun / to kill time, though. So a few games a day on a metro or whatever. So with no aspirations to actually improve I think I'm at the peak of my natural ability.