I'd recommend keeping it at one swap at a time.... maybe shorten the tie-time to delivery-time window just a bit... if you get too many swaps going at one time folks could get burnt out real quick plus ya run the chance of mixing up your submissions between the swaps.

There was a time I was involved in 5 swaps and it wore me out trying to keep up with who was who and what was what and which jigs went where....

Just my opinion to the question asked earlier about running swaps simultaneously....