I agree that there should be more than one per week. But, realistically, we can't do too many. I'd say 3 is probably too many. Maybe 2 per week? As for a system, we could just adapt the current system to include an extra workshop. I'm happy to submit something whenever. 25th of June. 2nd of July. I don't mind. If we make a schedule with two people per week, rather than one, we'll have a backup; like if somebody doesn't submit on time, or has something happen to them, or whatever, then there will still be a workshop. It's bound to happen.
I think 20 pages is too long. I don't mind editing/reading/giving feedback for pieces up to 10,000 words - but I think it's probably too much for some people. There should be a word limit. I think 4,000-5,000 is more sensible. Personally, I'd push it back to about 3,000 words. I've done a lot of workshops. 3,000 words is quite a lot. I don't really care, either way, as I said. I just want the workshop idea to succeed. If we get 10,000 word submissions, I think we'll be struggling to provide detailed feedback within a week. 10,000 is an incredibly long short story. Most short story competitions are up to 3,000.
How about 1,000-4,000 words, rather than 1,000-10,000 words?