I'm with you, DA. One turf condition that has not been mentioned and could extend the acceptable time frame, in my view, is recent aeration - solid tine or core. Caring for turf will never be all science or academic, no more than standing in the batters box trying to get a base hit -- and we don't know what pitch is going to be thrown or what the next batter is going to do. I went to turf school. Professors are important; they teach and conduct research. Whether it's soils, pathology, cultural practices, fertilizers, weed control, selecting and establishing turf, irrigation, etc. it is good to have the education as a background. Long after I graduated new premises have been tested and new recommendations have been made - some conflicting with earlier recommendations. You have to have a base, whether you learned it in the classroom or from years of working with competent people in the field, from which you can devise your own plans and make your own decisions -- and, sometimes, take your chances. I don't know who said it, but a quote that has always served me well is: When you attempt to make a science out of an art, you elect to be precisely wrong instead of generally correct. What we do is part science and part art. Sometimes I get in situations in the field that make me want to read published articles or look for answers in the discussions on lawnsite. Other times, what I really need is an enterprising young b@st@rd working beside me. When the ground is frozen, it is too late to fertilize (that has not always been thought by academia). When you know it will be frozen in less than a week, there is about a 85% chance it is too late. Very early Spring is not good. Everything else in on the table for me depending on many factors that are sometimes reduced to informed intuition. It is more complex than a two-dimension question and solution IMO.