For me, usually Mon, Wed, Fri are running days.
Tue, Thu and Sat are the gym days and the Sunday is lazy day
This is in ideal world But life is not on strict schedule, so I move things around, switching Sat and Sun or run on Sun and rest on Monday.
Sometimes I have to sacrifice the gym day. But I am trying to keep my pedometer happy - 14.5k steps per day!
Keep it three days per week. Try to give some rest to your legs in between.