Middlemarch:
I don't wish to brag - and please don't see it as such - but there are many times that I have had excellent and consistent results with a 96% to 99% "return" on a roll of film - 36 exposure or less. For example, I spent one summer photographing (available light) a series of plays for a summer stock theatre in the round in the following manner:
In order to achieve high consistency, I took the time to read the play, if time permitted, which I did most of the time; spent some time at the dress rehearsals before I shot the play to get a sense of the action as the play played out; took meter readings (incident method) on the dress rehearsal before the final one and memorized the basic exposure and also whether the light went up or down by a half or a full stop; shot 11 13 rolls of 36 exposure each of Tri-X and developed it in Diafine making certain that all of my temperatures - from start to finish - were within 1/2 degree and that the agitation was consistent throughout the entire developing process, and easily blew up whole or partial segments of the negative to 11 X 14 prints with minimum grain and high acutance. With very few exceptions, all of the negatives on each of the many contact sheets exhibited consistent exposure. Of course, I made use of a Leica rangefinder, the 35mm and 50mm Summicrons and a Leitz Valoy II enlarger.
The same consistent results can be easily under far less stressful conditions, i.e. everyday photography - preferably using a handheld meter and the incident light method and carefully looking through the viewfinder before tripping the shutter.
My suggestions for raising one's consistency is to begin treating your photographic efforts as if you were using a 4 X 5 view camera. In other words, slow down a bit and look at both the parts and the whole before tripping the shutter.
For example, I have a wonderful shot of a model log cabin and sawmill that was taken with a 28mm Elmarit M (borrowed from a friend) on my Leica. The only thing that really "spoiled" the effect of making these model buildings look "normal" in size was the fact that I forgot to more carefully look in the viewfinder before tripping the shutter. Located at the top of the frame - almost out of view - was a few power or telephone lines. The slide is still a "keeper" in my book, since I was still able to make use of it when I taught photography and use it to discussed and illustrate one of the effective uses of wide angle lenses, i.e. moving in close and making things seem bigger than they really are and to also illustrate the need to "look" carefully before tripping the shutter release.
Consistency of excellent results are not difficult if one pays attention before tripping the shutter. It's the real "keeper" photographs that are often difficult to achieve because not everything "gels" at the decisive moment, i.e. your subject looked fine through the viewfinder, but the resulting photograph shows that she/he blink. etc.
Hope this discussion is useful.
Bill