I'm currently scoring a piece for piano and I'm having trouble notating slurs. Looking at other piano music, slurring seems rather arbitrary (as opposed to writing for strings or winds where slurs determine articulation). The piece I'm writing contains lots of repetitive eight note arpeggiated figures in both hands, so there's often not a clear melody or phrase. I noticed that slurs in piano music rarely span more than two bars. I also read that slurring is not always necessary in the left hand.
So should I just follow my instincts when writing slurs, i.e. write what feels right and not overthink it? Or are there some exact rules I'm not aware of?
I'd love to hear people's input.