Agreed, separate screens are easier to mess with if you’re growing multiple plants. Even if you start them at the same time and have the same nutrients etc… one can mature faster than the other. I am about to harvest my first scrog soon possibly next week depending on how fast my trichomes turn but I do have one that is slightly more ready than the other even though they are the same strain. I think you can get away with one plant in a 2x4 honestly. I have a 3x3 and could have easily done just one.