I think many have hit the nail on the head when they mention they either don't know what a zone looks like on the neg or took quite awhile figuring it out.
After 35 years of doing B&W I think I have a pretty good idea of what a good neg should look like. At least for me, with my techniques, my water, and my equipment it appears suggested asa's work for me. Even for trannies as well.
My main point in all of this was to stress the importance of getting your equipment calibrated so at least you are starting from a reasonable and known benchmark.
Shutter speed is just as important as meter calibration. If my shutter is 1/2 stop to slow it will impact my negs in exactly the same way whether I use it on my field camera or on my monorail. Unless you have something seriously wrong with your camera's interior there should be no difference.
IMHO there has been way to much VooDoo applied to the analysis and generation of B&W negs. Many would benefit from learning to get a great negative using suggested asa's, and developing times utilizing regular developers. This of course with calibrated equipment. Once this is achieved then fine tuning could be done. Of course they would also have to learn to print this negative as well before any fiddling is done.
This said I do use the ZS all the time and feel very comfortable with it. I can spot what zones are what in the field and know when to use N+ etc for the final effect wanted. I know of one person who has come up with very customized developing dilutions and exposure placements thru much testing. He gets the results he wants. But guess what? His meter is 1.5 stops out. I suspect he could use much more mainstream developing times and zone placements if he had is meter calibrated.