I don't know how many different ways I can explain this.
If your interest in the Semi-Stand process is because you get sharper negatives that is not the case. There is an appearance or impression of greater sharpness because of dilute developer becoming exhausted at the boundaries of tonal differences. The greater the tonal differences within a given scene (such as texture) the greater the adjancecy effects (perceived sharpness) will be.
My interest and reason for using the process has NOTHING to do with sharpness and has everything to do with MICRO CONTRAST. Because I shoot mostly in very flat lighting, I do not like shadows, however, I have become infatuated with Azo for a number of reasons. Unfortunately, Azo has a considerably longer tonal scale than even the softest of enlarging papers. Consequently, with conventional means of developing film it is NOT POSSIBLE to achieve acceptable results in this combination.
While I do shoot mostly in flat light, my other interests lie in interiors of buildings where strong light can be included from an outside source. I have said many times that the Semi-Stand process is the best of both worlds, I realize now I must add for me to that phrase. Not everyone shoots in conditions which I find most interesting.
Just to re state, Semi-Stand and Minimal Agitation methods of development maximize three areas of the negatives DNA. You realize maximum film speed, maximum shadow contrast (micro contrast) and you realize maximum highlight compression because of the dilution of the developer. This sounds somewhat contradictory but it is not because of the control one has over the micro contrast of the negative. How else could I make a full range Azo grade # 2 print from a scene where the light meter showed no more than three zones difference in tonality. At the other extreme I made photograph where the lightest area was Zone 15 and the darkest area to show texture was Zone 2. Each of these prints respectively Penile Colony and Prison Cell Block were processed using the Semi-Stand method and have been seen first hand by a number of APUG members who can attest to that statement.
Lastly, if I was the type who shot allot of film I might not be willing to commit the time necessary for this development process, however knowing the results possible the point becomes moot. A two week trip to the west for me would likely yield a negative made at dawn and one at dusk, with the mid day left for travel and food. If my interests were to make negatives during sunlight hours, such as nearly all of Michael and Paulas work on Azo then the process wouldnt have near the impact that it does for me.
There will always be debate about technique, however, when someone tells you that they dont believe there is a difference, one of three things is present, either they dont make photographs in the lighting conditions I do, they dont use as long a tonal scale positive material or they are being less than candid.
Daniel, I don't use any screens between film and container, I always presoak for 5 minutes. I have been asked by many photographers who have struggled with unevenness how I agitate and when I explain I use a JOBO cleaning sponge or a circular type rod with 1.5 to 2" diameter disc in an UP and DOWN gentle thrusting action I have been told their problems with unevenness vanished. However, initial agitation is more vigorous then subsequent agitation cycles.