[Olly Lawer]"I have already created 20 or so sequences. Am I going to run into trouble if I create too many?"
The number of sequences is seldom a problem. It's the number of open sequences that often bites. So, proceed without fear... And, keep in mind that you can always open a brand new project at any time, and you can just copy and paste only the sequence(s) you actually need into that project, and it will run like a champ.