I NEVER do the same exact routine twice in a row. I really heavily on constant muscle confusion for growth. But I always make sure to either work both wide and narrow grip in the same workout, or if i don't get wide grips in a workout, i get them in the next one. Same with narrow grip. Which way works which part of the bicep isn't all that important IMO, what matters is that you're hitting both heads consistently
Lee Haney once said that wide grip is superior to narrow or shoulder width grip because it allows the biceps to supinate the wrist which works the muscle completely.