Duh! I completely missed the fact that the TIME field specifies Start and End of the program period. I guess I assumed it was Start time only and I managed to ignore the extra fields. I can certainly live with the way it is.
But, IF there were a choice, I would prefer something like I mentioned, because specifying the number of cycles explicitly describes what you desire, with zero chance of error. Achieving the desired results through a calculation that implicitly defines them would be a distant second choice for me. As a user, the program end-time is one of things I don’t expect to have to care about (other than making sure the day doesn’t end before the cycle finishes).