Just because you CAN do something does not mean you SHOULD.
Let me describe a recent jobsite. A large store is divided into booths, about 10x10, and each booth is in turn rented to a contractor, to showcase his wares to the general public. One booth might be a plumber, the one next to it a siding contractor, etc.
Each booth has a few receptacles, and each circuit serves four booths.
My customer had added a receptacle, only to have the circuit go bad a week later. Was the problem with his wiring? Nope. It appears that another booth ran a nail into the conduit when they covered up one of their receptacles.
I say 'appears,' as we have no way of knowing where the fault lies, or pulling new wire into the pipe - until that guy takes his wall apart.
THAT's why we don't bury splices - no matter how well done.
