I can't recall for sure but the other day we got a 8:10 or 15 am setting can't recall for sure at the moment for CRT. and I was told that the setting starts at 8:05 not 8:00am and they set so many people every 5-10 min so that it ends up having people eat at different times so that the flow of customers isn't always full full so that the wait staff can handel the table flows. So lets say they start the day at 8:05 they are not setting 122 tables which is what I think is in the CRT. They will stager the families throught out the 1st hour so that in case some eat slower others wont hopefully end up waiting to much time past their PS time.
Hope this makes some sense, I don't know if I am explaining it as well as the WDW CR did.