I always have a backup light in my bag fully charged anyway, so if I forget, I can just run that and live with an only partially charged backup. I wouldn't care if my bike comp wasn't working, but a single CR2032 cell runs it for 2 years so that's never really a problem. My phone runs 2 days on a charge and I have to charge it whether I ride or not. My BT headphones need charging about every 3 days and again, doesn't change if I'm riding or not.

I don't really NEED to charge lights during the summer, as I'm always riding in daylight. I do charge and ride with them but if I was ready to ride with no headlight, I'd just ride anyway. In winter I have to charge my front and rear lights, but my winter lights all run off a 7.4v pack. There's a charge cable in the garage where I park, I plug that in when I get home and unplug it before leaving in the morning.