Erratic email checking?

[anticowboyism]

Looking for some ideas/answers to why my email has not been checking consistently on the schedule I set. Sometimes my phone will be on all day and I will not see any new emails. Then the next day I will reboot the phone and a whole bunch of emails from yesterday will show up. And other days it seems to get my emails as scheduled every 30 minutes. I do lock the phone and put it in standby most of the day. I notice it likes to check my email mostly when I give it attention, turn it on and off, or use programs. But the phone should still check my mail when it is in standby and locked right? This is on the Sprint Touch