Whether or not a single person can reach max lvl in a certain amount of time is irrelevant. What is relevant is, considering the conditions on a particular server, how many people can do it, and if you factor in the fact that you need plenty of very specific adventures, buffs and interaction with other players, the answer is : not many.
Certainly not the new ones that have no comfort of owning 100 frozen manors, 5 MMAs etc. and are already a couple years behind when it comes to building up the infrastructure