I virtually never use rolling as a method of applying Screen paint. Any high performance / high contrast paint will have the tendency to show any defect or failing in rolling technique, to the extent that unless a absolutely perfect job is accomplished, something adverse will always be noticed.
Now if one uses a simple Flat White or Gray, the opposite is true....because such Flat paints are used specifically to hide such things. Once one moves into Satin or Eggshell paints, blemishes or defects show up easily. Go to Semi-Gloss / Gloss, and the surface must be perfectly prepared, and paint application perfect. because high performance DIY Screen paint contains reflective elements, is usually some degree of Gray, and has a higher gain than any Flat paint, it too is unforgiving of errors or surface defects.
It is no accident that cars are painted using Spray guns, not rollers or brushes.
DIY screen making is all about trying to optimize the end results....to the extent one can do so. Those who can only ever aspire to roll on paint must out of hand accept that they are limited to lessor performing coatings. In some cases, where a very high lumen output PJ is being used, and a surface is adjudged to be very smooth, a simple Flat neutral Gray can be rolled on to good effect using the right type rollers, a good base paint, and correct rolling procedures. But miss the mark on any of the aforementioned (...especially rolling technique and / or type rollers used...) and oops.....even a Flat paint can't make up for the goof.
So.............in answer to your question: You roll up & down, maintaining what is called a wet edge, you do not overwork the paint, and you use 3/16" nap, very good quality rollers.
That's why I spray. Point and shoot, baby.
Well, ok....perhaps it's not that simple. But it is a far less worrisome process that also virtually assures a perfect surface every time.