I notice Friday and Saturday is a little busier, as previously said because more expats out. But do not think a holidaymaker will really notice that much difference, or probably will not know what day it is anyway!!
There is never a quite day in Patong, not like back home say on a Monday or Tuesday night, my old town was usually dead. Just before I left Thursday became really busy and everyone was saying thursday is the new saturday. In patong everyday is like a saturday!! or is that everyday is like a new thursday?? feck its difficult getting old!