I agree with Zizaco on these points!
I would not be able to participate as frequently as every 3 months, and I believe engagement would be higher if it was less frequent.
The monetary prize is a great incentive for new indie devs looking for opportunities to get their games on steam. Finding a sponsor for the monetary prize would be the best solution all around. I am not opposed to a small entry fee for the jams if necessary, but I worry it would prevent many people from joining the jam.