HTC Incredible : Gmail Messages Should Appear On Phone Without Having To Refresh Or Manually Sync Gmail App

im not an expert on how push email works, but my understanding is that gmail messages should appear on my phone without me having to refresh or manually sync the gmail app. for a reason unknown to me, sometimes this works and sometimes it doesnt. at night, i shut down wifi and the mobile network to conserve battery and start up the mobile network when i leave for work in the morning. i get notification of new yahoo email, thru the htc widget, almost instantaneously, yet gmail doesnt come thru until i manually sync the gmail app. then during the course of the day, sometimes gmail messages get pushed right thru and other times not at all until i manually sync the app. meanwhile my yahoo mail comes thru flawlessly.

considering gmail is supposed to push and the htc widget does not, this is the opposite of what i expect. as far as settings, i have auto sync enabled for both the device and for the gmail app. while i always assume user error until proven otherwise, in this instance i think i have all the correct settings, which makes sense considering sometimes gmail does get pushed. its just erratic and unpredictable. anybody got any ideas what's going on here?