Does second/revision hair transplant surgery boost the result of first surgery?

It all depends.  If you had a poor result from the 1st hair transplant surgery the 2nd surgery may be different.  The question is why would you have a second surgery if the first was so poor.Your particular case doesn't make sense because hairs do not grow 2 weeks after surgery.  Maybe it's from the 1st surgery.  It really doesn't matter.  What matters is how it will all look in the end.

Without seeing any before and after pictures of either surgery, it is difficult to make an assessment.  It is atypical for you not to have seen any results after a 4500 graft transplant procedure.  Best to discuss this with your surgeon.

It is very strange not to have any growth during the first session especially after 12 months. Of course a new session may, in many times, be required to achieve higher levels of density, however this has nothing to do with the poor results of the first procedure which should have been visible as well. Poor growth may be related to poor medical team's expertise or technical issues during the session.

After a year would take a failed transplant and turn it into a success. Considering that I have been in the field 24 years and performed over 15,000 surgeries, my experience must have some value here.

Most of the hair grows in between nine and twelve months. Mutually we wait until on year after the first procedure to odd the second one so we don't transplant on top of the first one.  The hairs that are coming are most probably the hairs from your first surgery.