Manual Sync issues

 I set my phone at night "Off Peak" hours to do a manual sync but it just doesnt seem to work. If I set it to increments like 15 minutes and so forth it works fine...what gives? Anyone else have this issue? It's like Manual is really "as item arrives", makes no freaking sense! Also does anyone know what "Once a day means"?

Khassy I understand what once a day means just wanted to know when once a day Is it when you set the once day? So if I set it at 6:00 pm then it will sync the next day at 6:00pm? Also Manual sync is not working for me during off peak hours. That is the reason for my post. If I set peak times from 7:00 am to 11:00pm and I set the the sync times to off peak I am still getting them as they arrive I have tried over and over and over again and have looked around and just dont know what else to set.

I realize that Gmail auto pushes as emails come in so I turned of sync'ing all together for Gmail. The challenge is my exchange account, I have it pushing during peak and that works fine but when I set it to manual during off peak I still get emails being pushed to me. I do not want to silence the notifications as they are tied to texting notifications as well as email which sux! I wish there was a way to have seperate notifications for each app but the really issue here is that manual sync does not work during off peak hours. I have set up the account to stop off peak at 11:00 pm and i am still getting notifications pushed to me all night, what am I missing?