Please excuse the long pause between replies. I was just looking over the comments again and I noticed that you use Ilford Delta 100 film. I think traditional grain films are better for pushing and pulling than the "T grain" emulsion films. Precise exposure and development are critical to obtain good negatives with the "T grain" films. Traditional emulsion films such as Ilford FP4 or HP5, Kodak Tri-X, J&C Classic 200 or 400, EFKE 100 or Foma 400 can be pushed and pulled easily for better and more consistent results in my opinion.