After reading that the 6s performs on par with a 5s while in LPM, I'm thinking why not use it all day or on days you know you'll be gone a while? This may be especially useful for 6s owners who are usually just casual smartphone users like me. Videos and web browsing don't seem to suffer at all. In my little test on a 6s, I'm at 3 hr usage/14 hr standby with 72% remaining.