MS Exchange Inbox subfolders not syncing on Fetch

I have been running Exchange on my Iphone with no problems however i do have one question.
When i select PUSH all my subfolders are synced to my MS exchange account no problem.
However when i disable PUSH and run FETCH (mainly to save battery) only my inbox is synced. The subfolders will now only sync when i click on them.

Is this normal behaviour. I would have thought if it works via PUSH then it should all work via FETCH.

Thanks for the help.