Steve, if you’ve not done that sort of thing before it can seen odd, but basically with an 8 track (recorder) with stereo out you can only transfer two tracks at a time, where one track is panned hard left and the other hard right thus creating two mono outs as it were.
The problem occurs when transferring multiple tracks (8) the tracks will drift next to each other over time (the longer the transfer the more the drift) especially from say 8 track cassette or even analogue reel to reel.
So using say track 1 as a reference timing track on each pair 1,2 1,3 1,4 etc. will provide a timing track to check where the drift is occurring at any point in the transfer.
The slight downside to transferring 8 times 1,2 1,3 1,4 verses 4 times 1,2 3,4 5,6 etc is that you now have 8 tracks that have varied randomly rather than 4 pseudo (stereo) tracks, the positive being that each track using the 8 times transfer has a reference.
Hope that makes sense?