The guitarist I play with writes songs containing some dodgy guitar riffs including hammer-ons, pull-offs, pushes, slides and generally too many notes. . . . and then wants me to play them in unison. . . . and then counts the song in too fast when we're on the gig!!!
Apart from that I don't get stressed by bass lines. Work them out, practice slowly then speed up.
I did feel pretty satisfied when I put together good slap-less versions of Let's Get Serious and Uptown Funk.