I would look at the roster and stat histories of your target schools. How many of the upper classmen had redshirted - this will tell you your answer. Equally important, look at the stats of the upper classmen when they were freshman - how many got significant action, some action, no action, redshirt? At my son's school (mid-major D1) every upper classman starter had been a contributor when they were freshman. I'm sure different schools and coaches have different ways of doing things, but it's useful to know how they operate.