Pretty much any house you walk into in America has compression shutoff valves at the water line hookups under every sink and behind every toilet in the house. These compression valves where never designed to last. They must have all been made in the most cost savings oriented factory in the world because the compression aspect of the valve just simply fails after any period of time longer than about a decade.
Now, when I’m talking about a compression shutoff valve, what I mean is the multi-turn angle valve for the hookup lines. Here's a photo:
A multi-turn angle valve shuts-off the water via compression in the valve. It’s the compression aspect in the valve that is guaranteed to fail after a lot of use or simply the passage of time.
Job #1 when I’m doing a rehab is to replace every single compression shutoff valve in the house with a quarter turn shutoff valve. The quarter turn valve is in essence a ball-joint valve and you can be darn sure that puppy isn’t going to fail.
Below is a photo of this kind of valve.
Once all of the shutoff valves are converted to the quarter turn valve, I can always breathe easier when I'm having subs change things out in the bathrooms or anywhere in the house where water is involved. Other than a fire, water leaking anywhere in the house is the most destructive thing that can happen.
If you have your own rehab crew, I recommend teaching someone on the crew how to change out these shutoff valves. If you don't have a rehab crew, heck just learn how to do it yourself. It's a bit of work but you can learn to do it. Plumbers themselves would love to charge you something like $50 a valve and there's just no way you should be paying that. You can learn to do it yourself and save a good chunk of change.
If you have questions about why I'm kind of obsessed about this, please feel free to ask.