I have no time to practice so I get to the track early on race day and run a pack in each car just like a lot of others. A lot of practice is great for you but not so hor for your equipment.
Especially with todays complex boosted ESCs, running your car for any longer than the amount of time a race would last can be a bad idea. I can't speak for everybody but all my cars/trucks are set up to run 5-7 minutes. Much more than that and they get too hot. That includes motors, lipos, and ESCs. In the rare case that I have time to practice, I go to the track with 3 or 4 cars and all my lipos....I have 10 or so. I alternate cars and charge used packs as I drive. If you could get an hour solid of track time in a week that would be phenominal. I spend 7 hours at the track on race days and generally get 30-40minute of track time which includes practice and racing.