I apologize if this has been covered elsewhere but I wanted to pass this along to those who may be interested. I have begun using previsualization of tonal relationships at the printing stage. By this I mean that I have determined in my mind how a given zone tonality will appear on paper. From this I am able to more rapidly and more accurately determine the burning and dodging that I want, how this will appear in the print, and how much time is involved in each of these considerations. I began this process for myself by making a test strip of what a Zone I through Zone VIII tonality would represent on the paper. This was done by printing my film test negatives or calibrated step wedge on paper. The calibrated step wedge works really well for this...however, one could also do the same thing with film that has been accurately exposed and developed. I find that my considerations in burning and dodging rarely if ever amount to increments of less then 1/3 zone or stop. I have found that with practice that I have developed a mental picture of this tonal scale and from that I can make the necessary time calculations at the burning and dodging steps. For instance, I find that my print base exposure is 21 seconds. If I find that I have an area in the print that I want to have lighter by 2/3 zone and another that I want lighter by 1 1/3 zone. I dodge the first by 7 seconds and the second for 14 seconds of the base exposure. Continuing, in the example above, I find that I have an area in this print that I want darkened by 1/2 zone. I then burn this in by 5 seconds after the base exposure. I then finish the printing by darkening the edges 1/3 zone which would be 3 1/2 seconds. In other words, I have taken to thinking in terms of tonal scale rather then fixed times in seconds. Hope that this helps.