change category on a regulair basis ensures it never get to professor, it is 630 gc or arround that for full professors, near nothing for a newly novice for half the effect and flat rate at that, meaning while twice the effect is worth it at say 2-3k acres it is dragging you down and hurting you at 500, if you have 120 scientists it adds more than 75k nw to your province no matter if at 3000 acres or 5 meaning a province at much more acres but no professors can still make optimal hits as far as honor is concerned, a bonus is that you naturally switch between several categories and experience various bonuses at various times which can work out well if you know what you are going to need in a few hours.