It would really be more convenient to just have one more button in setting to just manually back up the watch.

I know that the watch will be backed up once a day (1AM-5AM) IF watch is connected to the phone and phone battery is at least 30% and screen is off. 

I don't connect my phone and watch to the internet or to each other overnight when I sleep. However, I will connect my watch to phone after I wake up to sync the collected sleep data but it's always after 5AM so no back up is saved.