The fitter should be able to see your swing and narrow the choices down for you and many times there could be more than one combination that could work for you. I have mixed feelings because, at least for me, grooving a swing on a launch monitor under perfect conditions is not the same as taking it to the course. I ended up having my clubs tweaked a few times after playing them, but a good fitter should work with you to get it right.
I let him worry about the tightest dispersion and shot height while I tried to articulate what I liked and didn’t like. For me it was mostly about what looked good and felt good while he crunched the #'s.
For a # of years I basically fit myself. I had been through a couple of fittings and wound up with some clubs I loved and others I didn’t care for. At least the fittings gave me a good baseline of what I needed so then I experimented. This was great when I had the time and passion for building clubs, but it can be a slippery slope. You can build a nice club very inexpensively, but building a lot of clubs as you experiment can eventually add up to a PXG fitting that includes golf in Scottsdale.