vaporization of water from a surface of mycelium stimulates formation of pins.
this understanding helped me quite a bit watching my shrooms grow and fanning and misting and all that. if your mycelium looks fresh, not dry [not soggy and wet also], you don't need misting at all, from my experience. bubbler and damp perlite should provide enough humidity.
but also, watch it, if you see there's not a lot condensation on lid, mist a bit. when misting, try to make the smallest water droplets possible.
and mostly, use common sense