Placing the 'soft' exposure and then the 'hard' exposure makes all the sense in the world to me. But the subsequent burnings at grades other than 0 or 5 pose's a problem in my mind as to their most effective order. If your proof print of grade 0 and 5 indicates a need in some areas of an additional grade 3 density do you place that density before or after your grade 5 exposure. Does it matter? It seems it would/should matter but perhaps it would have no visable effect.