Our workflow sounds similar, except that when my system reboots, Chrome is frozen for a minute as every tab tries to reload simultaneously, following by confusion as any youtube tabs all start playing.
On Firefox I had no such issue as each tab would only reload on focus.
Chrome on my girlfriend's PC did that in the middle of the night once or twice. I guess Windows or Chrome decided to update or something, not sure which, but all the YouTube videos in all the tabs started playing in the earlier hours of the morning.
On Firefox I had no such issue as each tab would only reload on focus.