I use 334-3 (7) when a wall's studs are on edge and I have to install a run parallel to the stud to the outlet or switch. . .sleeve the MC with EMT and move on.
I have rejected for sleaving mc cable in 1/2" conduit without an mc connector where it enters the conduit even though the conduit terminates in a 4s box w/o concentrick ko's which is wire grounded.