The way we do 60/120 four fletch is with the 3 fletch indexer and only use the cock feather and one hen feather position, then turn the arrow 180 degrees put back into jig and put on another hen feather and cock feather. My nocks are always glued on before fletching.
If you are right handed one will want to rotate the indexer counter clockwise to that first hen feather position. If LH rotate it clockwise.
If using the JoJan fletchers just put on the cock feather, then turn indexer counter clockwise(see note above) to hen position-put on feather. Then pull arrow out of jig, turn 180 degrees and insert back into jig-put on another hen feather. Then turn indexer back to cock feather position for last fletch.
Now if one is using a Bitzenburger or similar type fletcher where the clamps are held in place with magnets one has to do this slightly different. Insert shaft into indexer in cock feather position-then turn indexer couterclockwise(see note above) to the hen feather position. Put on feather-then take arrow out and rotate 180 degrees and put back in indexer-put on second hen feather. Then turn indexer back to cock feather position-put on feather. Take arrow out turn 180 degrees-put back in and put on last feather. Reason for doing it this way is for clearance when fletching. With Bitzenburger fletchers if you put on the cock feather first when it comes time to put on the coreesponding hen feather the previous cock feather will be underneath the magnets and wants to distort the alignment. Believe me the first time you do it you'll be cussing.
Here is what 4-90's looks like on the string.
And here is what 60/120 looks like on the string.
The real advantage to this alignment, and cock feather in, is to eliminate the hen feather in the 4:00 position which always strikes ones shelf and causes there to be a higher nock point than necessary. With cock feather in 3 fletch and 60/120 4 fletch(which is really a cock feather in 4 fletch) there are no 4:00 hen feathers hitting the shelf thus eliminating the needed higher nocking point.
By utilizing the effectiveness to of cock feather in 3 fletch and/or cock featehr in 60/120 four fletch to its fullest when one can lower there nock point. In my case I was able to lower mine almost 3/8".