Used the technique with the Fuji 90mm f2. Works well. I will try it with the 56mm at next occasion.
Why many photos? It's simple. You always get a distortion in your pictures. At 200mm it is almost completely nullified of course. But with shorter focal lengths, it is not. By shooting more pictures, you get every piece of your brenizer from a center-part of a shot. That way, you don't have to fuck with distortion problems. Other than that there is also vignetting. I shoot Brenizers in RAW mode and the RAW converters are not equally capable of compensating for the lenses' flaws as is the intern JPEG engine of the X-T1. Also there is really no need to use a special program if you have Photoshop. It can merge the whole shit together, compensate for some vignetting and even distort the pictures as needed. What's important though: You need to have some textures/colors in the areas further away from the subject, because Photoshop is looking for those. If they are absent the programm doesn't get what you would like to do. For Portraits it pretty much makes no sense to let it stitch together automatically, as all melted areas are strongly melted and lack details/texture/recognizable colors.