This may have nothing to do with nothing but I noticed in my first darkroom class that my test prints-each at 4x5 looked nothing like my 8x10 or 11x14 attempts at a final print, the larer prints were flatter and lacked the life of the small test prints. Since I had to do what the instructor wanted in his darkroom I could not use any filter at all. He was a jerk. The PIA pinstructor told me it was my fault and graded me down. A year or so later I had the opportunity to attack the same negatives with free graded paper. For some reason contrast decreases in 35mm negatives as the grain gets further apart in enlargements. Like you I just started printing at grade 3 to start and then moved from there. Maybe this is something many have stumbled on and never really gave it much thought.
I wonder what happened to the PIA.