I rebooted 7-8 times yesterday, all took 15+ minutes. I stopped timing it after the first couple of boots with the console attached.
The most annoying part was my UniFi Wifi stopped "working" when the DHCP server vanished for 15+ minutes, which was why i was debugging.
I generally don't reboot my router that often. Only for new software updates, so i'll live with the long boot time.