When we had a TT and nobody would use or need water in the TT until we got to our destination, yes, I drained the water heater after every trip. Was easy to do, increased life of the anode rod in the water heater, and was that much less weight we were moving down the road. It was kind of a pain, though, 'cause it meant that before every trip, had to get the big 'air bubble' out of the system, when water heater filled back up.
When we moved up to a Motorhome, things changed. Since we need hot water when on the road (for washing hands, etc), it was too much of a 'PITA' to have to fill that water heater back up and get the air bubble out before we left for every trip. Soo, now I only empty it at the end of the season when winterizing. It stays full all during the season. Yes, it will sit for a few weeks between trips, but we have not noticed any kind of bad smell yet. Does probably mean that I'll replace the anode rod a little more often, but the rod still looks good, after 3 seasons of camping.