In reply to The OP:
I had a look into this last year, but luckily managed to find a new job instead I think it's known as the real 3 peaks challenge, but google seems to now be full of lots of litter threads so it's harder to find the cycle stuff. Try here https://medium.com/@rmalpass/national-3-peaks-challenge-cycling-record-8742...
When I looked into it I reckoned that 3 days would need to be the target to make it worthwhile, but it'd be deeply tricky.
I got as far as
Up and down Snowdon (5 hours?) Cycle to Kendal ~ 170 miles = 13 hours. Sleep in Kendal
20 miles to ODG in Langdale ~ 1.5 hours; up and down Scafell ~ 5 hours then cycle perhaps another 120 miles then sleep
Then 150 miles the next day followed by Ben Nevis before dawn the following day.
Utterly shattering, but theoretically doable with the right group.
If I manage to get any fitness back them I might be up for trying this at some point.
Good luck if you do try it