My daily 60km commute with 4 hills would really suck with a single speed. I usually keep low gears while I get my heart rate up each leg of the ride, and then keep on higher gears when I am at my optimal HR, but as I am aging rapidly these days, it seems I stay on lower gears longer. Tooling around town with just flat spots, then okay I might do the hipster thingy a bit. Nowadays I'm not getting places fast, just making it there in one piece is the objective.