You can experiment with fit faster using a fit bike than waiting for a frame to arrive then building it up. This is how famed frame maker David Tiemeyer did it with his clients. He would propose dimensions then send the client to find a qualified shop with a fit bike and have the fitter input the dimensions into the fit bike.
You literally can do that today using the dimensions of the Fuji frame from the website.
The best part is that you can experiment with different dimensions
instantly. You can even experiment with crank length on these fit bikes as well. This is what the pros do.
A thread on the matter:
https://www.bikeforums.net/track-cyc...ing-track.html