i would say none, threads can be pruned, edited, or deleted by moderators

i am on another forum and the minimum post count to start a thread is 25, even after searching it is extremely annoying to try and think of 25 random things to post on different threads before you can create a thread you really want to make

Here's the final word....

0

as in ZERO.

(Unless of course you want to kill a community, and if so, just cut off the supply of new posters with arbitrary post requirements).