I think by default, it should be set to Global and remain at the top of the list. I'll only choose 'all follow' in extreme cases.

Also, have you ever considered making hellthread protection notes specific, as in long thread conversations, important signals around you can be missed, I use multiple clients in long thread conversation, there is a huge differences in notifications.

or making it entirely optional could be helpful since it's often not required.

By the way I am just saying, Take your time; I understand these things are complicated.