Whoever told you that had probably been taught by somebody who gained their experience in a previous generation &or had read a textbook probably written with a quill pen 
What comes back in the first few months is capability that wasnât destroyed by the stroke.
Is obviously a contradiction of the first quote and is more informed but as @Mrs5K said; putting time scales on an individualâs recovery is meaningless. It is possible to quote an average for a population.
Neuroplasticity starts from before the time of your birth and continues life long. After a stroke that plasticity needs appropriate nurture and opportunities if it is to operate in your favour because the non-use is plasticity that is not in your favour
âUse it or lose itâ as they say 
, and in contrast effort is rewarded with achievement
I find the story quoted here inspiring in this case the time scales were circa 30 years
Your opening quote is probably a self-fulfilling statistic for many. It takes a lot of faith and effort to continue doing exercises when the capability development is invisible until enough areas such as neurones muscles and tendons et al all operate together to give movement that confirms the investment finally has dividend.
Even tougher when what is being sought is return of senses such as taste and touch and sensation that doesnât tip over into feelings of pain, burning or freezing, electric shock, crawling ants, neuropathy,âŚ
Ciao
Simon
