Certain dealers update at certain times.  Maybe 
not to the minute, but within a couple of hours.  
Taro would be a good example.  They vary, but when 
I used to watch them more closely, there was a 
definitely a more likely time during the day to 
catch updates.

If someone else is catching updates more 
frequently than you, it isn't due to a timezone.  
It's due to someone having the time to sit in 
front of a computer all day and keep reloading 
pages.  :-/

JP