There isn't one. Unfortunately this has been a topic that comes up with every iphone. With current battery tech there simply is no reason to stress about when and how long you charge.
Use an apple approved charger. Plug in when it's available and convenient. You will be fine.
I will say that, based in your usage reports, your battery life is a bit low. But don't stress. Use it a while. Use it how you normally would. If it's still low apple should take care of you. Using it for a single day with a single charge isn't going to give you a real understanding of how anything performs, really.
Thanks.
How about charging? (as opposed to draining it). When you charge it, do you charge it all the way to 100% each time (or is best not to charge to the max) eg. do you charge to say only 80%. Or does it not matter so much with recharging?