I'm fairly new still, but I've noticed certain maps I'm much worse at than others, mainly being pretty awful at maps with lots of simple flowing patterns and double-taps, like a lot of Sotarks style maps or lots of farm-style maps I tend to suck at. Doing a 4* like this beatmapsets/1297248#osu/2691260 feels more comfortable than doing this 3.3* map beatmapsets/1639480#osu/3346254 for example. I alternate since I could never get used to single-tapping so maybe that's why the latter type of map feels more difficult.