In addition to the enhanced 'triangular' pre-Covid peak hour services mentioned at #9, the leaf-fall service at one time used to work in the same manner - I think this may be what
@Bletchleyite is referring to in #7?
The line was renowned for poor adhesion, and an extra Cl 323 was allocated during leaf-fall, giving a long layover at Hadfield rather than the usual 3 minutes. I seem to recall the 323 was released by covering a short peak-only diagram on the Alderley Edge line with a DMU. This ran both peak and off-peak during the week, but not at weekends. I started my time with Northern at Glossop and Hadfield in late 2005, when this was still in force. I'm not sure it lasted much longer, and certainly not afer the major Northern timetable change in December 2008.
The single-track nature of the triangle meant that the inbound and outbound trains had to 'pass' on the different platforms at Dinting (as on the pre-Covid peak service), so in the morning trains ran direct from Piccadilly to Hadfield, then via Glossop back to Piccadilly, with the reverse pattern kicking in around around lunchtime. I think there was a train from Hadfield with no connection to Glossop at Dinting as the 20 minute service kicked in, but I'd need a timetable on front of me to refresh my memory.
There was at that time a steady flow of Hadfield - Glossop passengers, including quite decent numbers of school pupils, so this pattern suited that flow as well.