This was rumored to be an issue with iOS 4. Supposedly addressed in iOS 5.
https://www.macrumors.com/2011/10/31/turn-off-time-zone-sensing-to-improve-iphone-battery-life/
Personally, anything I don't use, I turn off. Also, if it's not that big a deal to handle manually, I turn that off as well. These include:
bluetooth (off - don't use)
auto time zone (off - I change manually as needed)
auto brightness (off - personally think its broken, and it's not difficult to manually adjust)
diagnostics (off - not big on having Apple peer into my usage)
location services (off - when at home, on - when traveling)
notifications (keep these at a minimum, every app seems to want to "notify" me of something)
equalizer (off - don't listen to much music on my iPad)
One thing I do keep on is I have "fetch new data" under email sent to "push". I do like to get emails as soon as they are sent. But changing this is supposed to save some battery life.