Four stands is very handy if you don't have a lift, and you want to do brake work or anything that requires space underneath and a level car. I use a different method, though.

I have two flat-top stands and two floor jacks, and I put one end up on stands then lift the other on the jacks so it has four points of contact. The challenge is to raise the two jacks at one end together so the body doesn't try to twist or fall off the stands.

Most garage jacks are open frame in the middle, so to make it safe to work under the car with the jacks in place, I put a solid brace between the top of the jack arm and the floor. Once the jacks are up, I put a length of 2" steel pipe with a flange welded onto one end upright inside the jack frame between the floor and the mechanism at the end of the arm under the jacking point. Then I lower the jack a bit so the pipe is bearing the load. It's as or more safe than a jack stand - it can't drop, and the structure of the jack keeps it from tipping.

Cheers
JJ