Not sure why this isn't mentioned anywhere, but doing a domain in co-op mode gives twice the friendship xp, and I find this very helpful for when you want to focus on
Genshin Impact: Trick to get 100+ Companionship EXP every day without spending Resin
What exactly the new crafting recipe for mystic enhancement ore gives. : r/Genshin_Impact
Small tutorial on how to farm Friendship EXP : r/Genshin_Impact
FARM DAILY FRIENDSHIP EXP PAINLESSLY | Under 1 Min Video Fastest Random Event Inazuma - YouTube