Eh, all my Kindles spend most of their time in a pile on my shelf, and I've yet to encounter any issue reviving them from their "oh noes, battery is empty" shutdown
.
(f.g., earlier this afternoon, I booted a Kindle Touch that I last touched in May).
You just have to remember to unplug/replug them once they've rebooted, as some of them stay in trickle charge otherwise.
(... and also not to leave those with RP+CRP installed in diags too long, as, again, weird charge behavior there).