This was a 'rulings over rules' situation in the game so I didn't want to make a specific list as it could get quite long, and I run the risk of forgetting things. "Does it make sense my character can do X while maintaining focus?" If yes, then you can. If not, then MIND save.
I would rule walking doesn't break focus as humans are quite literally built to walk. However, walking over terrain that would require your attention (rubble, steep hill, etc) would require a MIND save.
Unlocked Door? No. Stuck/Locked Door? Yes
Mostly just maintain internal consistency. Don't rule it one way one time, then another way another time.
