There are two kinds of “bleeds” for brakes. There’s a mini-bleed (I’ve also heard it called a bubble bleed) and I tend to do that every couple-few(tm) weeks since I learned to do it. It’s not a full/true bleed; you’re really just getting air out of the system.
A full bleed I tend to do once a year, but I may do it more often than that if I keep riding as often as I do.
Mini-bleeds are fairly easy; full bleeds are more time consuming. Anyone who is unaware of how to do either can find vids from GMBN, Park Tool and even Seth’s Bike Hacks/Berm Peak all on YouTube.