As others have said, it highly depends on the terrain, how much weight you're carrying, your fitness level, and the gears you have. I have 24 speeds: 26-36-48 on the front and 11-32 on the rear. Most of the time I'm in the second gear on the front and vary the rear as needed. But on my preferred route heading home, I use every single possible combination. When I'm doing 25-30mph down a hill and want to pedal even a bit, I need to be in the top gears. When I'm climbing a hill that maxes out at 13% grade, I need to be in the lowest gear or else I'd have to walk it. I guess I don't need the other two gears on the front, but then I'd lose some speed on downhills and would need to use other, less direct routes on the way back.