I try to shoot enough to have a good practice, and not go much over 100 to 150 rds. I find myself just shooting if I do, rather than working to improve.
I like to warm up too-- we all get better as we go along-- but starting out cold from the start, with a timer, drawing from concealed is a truer test of our ability.
Can be a little discouraging to see your draw times and hit % less than optimum when you're dead cold, but I don't see myself having time to warm up when the "elephant" show's up, with Murphy right behind him.
Of course not all shooting is SD practice---if we're talking target shooting, load testing, or just having fun, then just go for it.