I have a jo jan multi (used to have the mono fletcher until I upgraded), and once it is setup it does a fine job of fletching the shafts. Just keep the clamps numbered with the location. Then you can notice if any location is not working correctly. I have not had this problem. It does flustrate me when I have to change shaft sizes, and I think about selling it, but having 6 arrows laying in it with the glue drying does count for something.
I will probably sell it anyway, even though I have extra clamps, and nock revievers, just because I use fletch tape for most of my fletching and glue for other's shafts so one fletching at a time isn't super important any more. Plus with one at a time the single jig is probably more consistant (as mentioned above) and the magnet on other models are probably more accurate.
I hope this helps.