Re: My Battery lasts all day...
I use an iPhone 6, and if I'm travelling I tend to switch the phone data side to 3G or even 2G and reduce polling to every 30 minutes or 1 hour (4 email accounts and a private cloud feed for calendar and contacts sync). If I don't get too many calls and I'm in a city (read: strong signal) I have no problem getting a full working day of use out of one charge.
There is no material issue with receiving email or messages slower, but it certainly has a major impact on power use.