Restarting a thread after 3 months already feels like thread necromancy in many cases.
Some high-quality threads can last longer than some weeks and would benefit from the 3 months limit, but more is definitely not needed. In an exceptional case your high quality thread needs to be re-opened past this three months limit I believe it is possible to ask a moderator to do so.
Maybe it would be nice to get a dynamic auto-close time for threads.
For example any thread posted by Bakster Kane could be auto-closed within 3 days rather than 3 months without loss of quality.
Seeing the sheer amount of his threads that had to be manually closed in the past months, I believe that this could improve the quality of the forum.