How long would you leave an iphone on charge?
I know some people either wait until the phone turns itself off to charge or they wait until the battery gets to below 5%.
I've found my iPhone to be a bit random with the charges.
Sometimes it only takes 3 hours to get to 100% but I've heard that you should leave it on charge longer to maximise it. With a full charge I normally get about 2 days standby, but obviously if I don't fully charge it then I get less usage out of it (meaning I unplug it as soon as it gets to 100%).