I have a Bitz adjusted for my “regular” sized arrows, ranging from Goldtip Ultralight to 11/32” wood. I have a Martin J-6 adjusted for my skinny arrows, such as Victory VAP’s. The Martin has slightly less helical than the Bitz, which accommodates the skinny arrows better. I have a Jo Jan that has a straight fletching clamp that I use on all the grandkid sized arrows and for some students. They all have their advantages. The Bitz is the classic fletcher first introduced in the 1920’s, I believe, with a strong magnet and pronounced helical. The Martin was about 1/3 the price of the Bitz, slightly less helical, with more adjustment options than the Bitz. The Jo Jan is the best engineered and simplest fletcher I have ever seen: it uses the force of gravity and the weight of the fletching clamp to perfectly position the clamp on the arrow every time, without needing any magnets or effort required on the user's part to press the clamp down onto the arrow.
Unfortunately, neither the Martin nor the Jo Jan are available anymore. A pity.
It has been so long since I have adjusted a fletching jig that I had to struggle to remember how to do it when a friend bought one recently.