Region plays a part. Up in MN, I did sun angle studies to see how far out I had to clear those trees to let in morning sun. It was much further than I would have to do in Texas. I found if I cleared all the way to Wisconsin, the sun would reach the first green early enough to avoid frost! (insert smileys, but its almost true.)
North South holes need more clearing for sun than east west ones. Oaks need wider clearing than pines, due to larger canopy.
Clearing width is also a function of the irrigation budget - 2, 3, 4 or how many rows can we have. We match to irrigation coverage. I have seen some pretty wide clearing in wooded areas.
Environmental restrictions can reduce clearing.
Heavy woods cost perhaps $2500 per acre. Clearing 90 vs 100 acres only saves about $30K nominally, although you also have 10 more acres of irrigation (at 11 heads per acre, at $1100 per head) and grassing at about $4000 per acre. So, the total cost is well over $180K for that 10 acres of clearing.