As a GM in the SBA, I can say that the 8 week season is practically perfect, but can be exhausting if you're really active in terms of draft research, the administrative side (contracts/budgets, lines, posting TCs, etc.), and trade talks. Shortening the seasons would probably be a great way to burn out GMs, and I think there've already been issues with getting and keeping quality GMs... but that's just my perception, and isn't necessarily a fact.