my son and DIL use this cooking method. First they rigged it up in a cooler and maintained the constant water temp, and once they decided they like the process, they bought a sous vide machine. It's pretty interesting, and pretty tasty. Once the steak is ready they put a quick sear on the outside in a frying pan or bbq grill. I believe you can hold the steak (or whatever) at the intended temp for a long time because it doesn't exceed the desired temp. So you could drop your steak in in the morning before work and sear it when you get home.