Iirc I did two ~70-80 mile rides in '17 (my first year of recreational cycling) and one in April '18, before randomly deciding one morning to try a ton just before the late May Bank Holiday in '18.
Was pretty slow ~9.5 hours on the road including 3 breaks and a puncture repair very early on that nearly scrapped the whole idea that day, covering almost every hill of note near me, ~9980 feet. All with a ridiculous amount of stuff in a rucksack including an extra 2l of water, not allowing my back to breathe and ensuring I had to climb at a steady pace.
If you have access to enough fuel and liquid, most healthy people who have a bit of recreational cycling experience could do a ton IMO.