It's an individual decision.
I don't starch before rotary cutting because I don't pre-wash fabrics. There is enough starch in unwashed fabric to keep my cuts accurate. However, if I do have to prewash a fabric for any reason, I starch and iron it to restore stability.
Many people spray starch but I have always had problems with overspray and scorching, so I developed my own method for starching yardage. I mix up a solution of Sta-Flo liquid laundry starch and water, "paint" it on the fabric with a large wall painting brush until the fabric is saturated, toss the fabric in the dryer, then iron with steam.
For a fabric I want to use for backing a quilt, I always do the above with a heavy starch solution (1:1). If I am just restoring stability after prewashing a "bleeder" fabric, I use more like a 1:3 solution (Sta-Flo:water).