if you commute daily to ONE place of work then you put down commuting, thats whether its once a week or 7 times a week.
if you only use it for going shops/friends etc then you just put s,d&p
because if you travel to work on that one day and have an accident they will assume you do it daily.
most insurance companys will just charge you the difference in premium amounts(say £30/40) before they process your claim.
personally i would cut it back as i work for toyota motor insurance and know the rules in terms of claiming.
the only time i wouldnt suggest telling a insurer about something is when i know they wont quote a price at all if you told them, most companys will just charge you the extra premuim amount for incorrect info before completing your claim.