Ah fair and up to you if you stay or quit.
You technically should try to keep up your characters as best as you can for Guild Wars and such, like the stronger they are the better defense they are. But yeah, of course up to you and fair if you want to take a break from the grind :-).
I personally don’t do that many friendship campaigns and such, most of the friendship campaigns I have that I don’t use are for those under level 100 for the most part, no reason to chase Friendship Campaigns that are really costly. I could of course go with the power-ups, but then I would hamper my Disk Power gain which isn’t that optimal either.
If the enemies are over level 100 for a Friendship Campaign you don’t need for a character you don’t use, I say avoid that Friendship Campaign if so.
Might be true that you can have over 20 000 stamina, but you actually get more from using your stamina when you get it, like since you gain more from the stamina you earn over time than the stamina you earn the 3 bonus stamina times and doing 1 buy more stamina per say.
So yeah, I recommend spending your stamina as fast as you can as you get more from the stamina that way, or otherwise wait to use it until contests. Personally I use the stamina as I get it.
And for the Weekly Quest it goes as far as you can get I think, but remember to get the rewards tomorrow as you might lose them otherwise I think. Still nice work :-).