I can imagine realistic situations where a parent might spank by hand first, then use an implement, but never in order to "warm up" the bottom for the implement.
Perhaps they meant to stick with hand spanking, but it isn't generating the desired effect (or the kid is brazen enough to chide, "that doesn't hurt!"). Or perhaps they want to give a long hand spanking, but then "punctuate" their point with a few swats of a more fearsome implement. But in general it's hard to imagine a real-life spanking situation that uses more than one modality, and surely not a variety of implements (10 minutes of hand spanking, then 10 licks of the belt, then 20 with the hairbrush, or whatever...)
I feel about the same about stories where the spanking is done in various states of undress. If you're planning on spanking the bare ass, bare it right away. Again, the only way I see it really "making sense" to start clothed and progress toward less and less clothing is if the spanker is winging it and has to adjust to the spankee's reactions.
Anyhow, I don't mean to criticize anyone's fiction -- it is fiction after all, so go with whatever fantasy floats your boat. I just find certain "unrealistic" punishment scenarios surprising for their frequency here. But I often write stuff that is way too severe to be realistic (at least when I'm supposedly writing in the context of a sane and loving family), so various other types of unrealism are also fair game.
