Rotoscoping is in A LOT of films, but I assume you mean "fully" rotoscoped films. A Scanner Darkly was aided by computer software for the graphic artists in charge of tracing. Same software was used for the Charles Schwab commercials.
I don't know how long it takes, but more than one artist is usually needed for rotoscoping over the entirety of all scenes. If you want "A Scanner Darkly"-style work, it might not happen since it was assisted by privately-owned computer software. Rotoscoping basic stuff, though (like the lightsaber in Star Wars), really does open up some avenues for you, since you would only be tracing certain things. But again, I don't know how long it takes, nor its accessibility as a film technique for nonprofessionals.