If I buy a real chunka corned beef, I simmer it per directions, but in beer.
If I want to eat corned beef and cabbage and don't care to fart around for hours, I open two cans of corned beef, throw on some garlic, onions, caraway, & dill, and maybe some more garlic.
I shred up how much ever cabbage I can stuff up under the lid and it still sorta stays down, pour a can of beer on it, cover as tightly as it will fit, and light the fire.
After it boils maybe 15-20 minutes, I eat. See, eating the stuff was the original objective.