Easier, but still time consuming.
Remember - the phone runs off the battery at all times. It does not trickle charge, because trickle charging a LiIon battery causes fires.
So when charging, the instant it's at full charge, it shuts down charging. It then runs down to a set point, anywhere between 92% to 96% before actually charging up again. During this time, your charging light may be green, but the only way to have your phone at 100% is to take it off the charger the instant it turns green.
It may take days for that last percentage point to level out, rooted or not.