From a quick search I hear that he can only get XP from bountiful delves after 15 (mine is like 48 now) he also gets a lot more XP for the first daily per day.
Does that mean that I can leveling him faster with more alts doing bountyful delves?
Is the first big xp bonus for the entire warband or character specific?
I’ve never seen anything about it but going by other such design decisions this expansion it’s pretty safe to assume it’s once per warband (for the bonus if such exists). You can do it with all your alts otherwise 4 times a day.
Not sure if you can farm it on alts, but easy to try. Just do one of the bountiful ones, log an alt and go do the same one.
What you can for sure do is the 4 bountiful ones each day on your main, you dont need coffer keys, you can just do the delve regardless.
Ofcourse you can do them on an alt as well but if its just for farming Brannlevel id think your main would be faster.
You can get xp from a maximum of 28 bountiful delves per week, account wide (not 28 per character).
It is doable on a single character because you have 4 bountiful per day x7 days = 28.
After you did 28 total you get no more xp for the week.
ideally they need to make it so max leveling a delve companion should provide a mount or title or maybe a teleport to a delve spell ( like the mythic + teleports )