Inconsistent sync

[Guest ringer]

Currently syncing email, contacts and calendar and am finding sync is very inconsistent, especially as regards email. Sometimes I get notified throughout the day pretty much instantly when I receive an email, then other times I wonder why I have not received any email and check to find out that email has not synced for 12 hours or more. As far as I am aware, I pretty much always get a signal, so it can't be lack of signal causing loss of sync. Can anyone shed any light on what does/doesn't trigger sync to work? What is the algorithm within android that triggers a sync? Perhaps if I understood that, it may help me maximise chances of sync happening regularly. Am pretty sure this is an android problem, and not related to which flavour I am currently running (FLB1.2 atm) because it also happened before I installed any custom roms.