i don't cut in the rain either but there are times when the morning dew makes things wet. when side discharging or even bagging sometimes clumps are present and a second pass is required or you go around the whole yard with a blower.
we cut at the height of 3" or higher. weekly in most cases. sometimes more than weekly. we try to avoid bi weekly at all cost.
and yes there is a difference between leaving clippings around vs. clumps. side discharging alone leaves clippings around, but they will turn into food for the turf. clumps will kill whats under it and be present until at least the next service sometimes longer depending on if you leave it there and how large it is.