I have two rear wheels for my bike. One has a fixed cog and a freeewheel, this wheel I use on the road. The other wheel has two different sized cogs , this wheel I use at the velodrome a couple of times a week.

I use a tugnut because with swapping out the wheel a couple of times a week, and also constantly fipping the wheel for gear changes starts to chew up the dropouts and really it's just more convenient tensioning the chain expecially with out a work stand. The axle nuts don't need to be as tight as well.