it does depend on the cuts. short ribs or other cuts with large % of connective tissue call for longer cooking times. But your classic sear and serve cuts like filet and ribeye have no business cooking for 48 hours. Yes, it yields a soft steak, but what has happened is a larger % of the mayo globin (what people who don't know refer to as juices or blood) has been forced out which gives you a drier steak. Dry steaks are bad. take 2 ribeye, sear it 30 seconds on each side,twice, then allow it to cool thoroughly. bag separately and cook one at 56c to internal temp of 54 (time depends on size of Cut). cook the other for your 48 hrs. allow both the proper 3 step cooling methods. Afterwards, remove both steaks from there pouches, and then measure the liquids of both to contrast/ compare. You'll see that the 48 has Lost more juicy goodness. that's Not good. sure, you'll have a softer (read softer, NOT more tender) cut of steak after 48hrs. If you're very old and have concern for your denchers, than softer is Always better.
Again, longer sous vide times are meant for "tougher" cuts of meat, ones that you wouldn't grill to mr and serve. This it's why I believe that if a cook can't ace classic braising, than he/she has no business with sous vide.
As for meat temps, I'll pass the gift of the butter knife down to you:
My first ever grill job was at a Ponderossa steak house. I doubt many even knows what this is, but that's not important.
It was during the holidays, and the place was in a mall parking lot, which means open to close constant ass whooping
I explained to the manager (yep, manager, not chef) that I didn't know my temps, but could make some mean grill marks. He handed me a round tip butter knife and said "let the steak rest a minute, then press this knife on the surface. watch for the juices coming out. red= rare, brown= medium, clear= well." Sounded easy enough. It was not. But I quickly got the hang of it. cooking hundreds of steaks all night didn't give me much of an option. And it was especially embarrassing having the attractive waitresses keep coming back telling me I under/over cooked yet another steak. (just made THAT other task all the more difficult...)