Thank you to Jim and Dick. Flat creation is so easy with ACP Sched that I shoot them every dawn and dusk. At any one time I have 30 flats for each filter. Each morning I add any flats that were created the night before, drop the oldest, and create a new master for each filter. The whole process takes about five minutes. I just put a sticky note on my monitor it says "flats, don't think about them!". If you've ever attended a meeting of citizen astronomers the most talked about topic, the most disagreement is about flats. How many, how to shoot them, how to combine them. My advice is choose a method and then "...don't think about them!"

..george