It may not do this initially when it is new, but the Li-ion cell is so small, that I bet, that once you start constantly charging/discharging/recharging that small Li-ion cell, within a certain period of time, if you let that cell discharge to zero and leave it that way for a week, it will be dead and will fail to charge.
I have already fielded about a dozen posts with about a dozen or so Pencil users in each of these posts and this is the pattern I am seeing.
It may ONLY be isolated incidents of this so far, to date, but there is a regular pattern to these Apple Pencil failures.
Many of these Pencil failures have happened in less than a year!
Some have happened around or within the 6 month window, too!
So, we shall see if I am correct and my theory/observation holds, or not!
Enjoy your new Apple Pencil! Hopefully, yours will last more than six months to a year!
Have fun with your iPad Pro and Apple Pencil & Good Luck to You!