Why don't we just have turn based trading with turns of 1 or 24 hours and then have a blackout period near turn ends when relevant information should not be divulged?
It would be hard to enforce a true "blackout period". Traders trade on all kinds of information, not just controlled data. Wouldn't liquidity tend to be lower on a non-realtime exchange, because everyone is essentially trading on outdated information, resulting in worse prices than the realtime exchange?
But I know very little about this stuff, so maybe I'm completely wrong.
I think prices would be better for people not playing the low latency response game. Liquidity within an hour would probably cost a premium as you'd have to get the money from someone on the real time market.