PRP treatment frequency, after hair transplant

[Helogen]

Hi,
I'd like to ask about PRP treatment frequency.
I've had a hair transplant in August 2018. I was given PRP (5 tubes, receipt + donor) at the end of the procedure.
Then, my doctor said I should come again to continue the treatment after 3 months, 6 months and from there on out, every 1 year.
1. Does that seems reasonable?
2. The PRP treatment frequency isn't "exact science", right?
3. At what time points should I stop to check if the treatment is efficient?

Thank You!

[maxwell77]

PRP therapy frequently needs three treatments maximum spacing four to six weeks apart. Every 4–6 months, maintenance treatments are needed. PRP treatment has been shown to be a very effective treatment for hair loss in research. Patients can see positive changes in their hair growth in the first few days or weeks after their first set of treatments.