Of those who've failed, some completed the round but in over 24hrs; some didn't start; some got X distance and stopped.
On the basis that some who succeed have to be prompted to send in their form - presumably I'm psychic and just "know" that they have succeeded and all their details - working out who started, who didn't, how far those who did start got before giving up, etc. is not easy. I "prompt" folk to let me know how they got on but even then not all reply, at the end of July I contacted those 39 who had registered for June and at that time hadn't let me know:
3 responded that they had succeeded but yet to send in their forms.
16 responded that they had failed in some way (one didn't start as they had Covid so weren't coming over from Canada!)
20 have yet to respond so no idea how they got on.
So it's a very incomplete picture and I don't think we'd ever get a fuller one given the above.