I orginal thought about doing it that way, since my orginal was a single dir. The launch overhead, read database of historical files, scan dir, check current list, write database of new files, it is all a huge amount of unnecessary overhead.
Don't worry about the odd sleep calc when they don't mesh. I think in 15 second increments. Almost all dirs will be 1 minute, but a couple will be 15 seconds.
The code was easy, and the X errors in Y time was a breeze, aging off errors too old, etc.