At how many posts in a topic before you decide it's too late to join the convo?

1. I only ever make my own topics.
2-5. Early on.
6-10. Within the first page for plebs using 10 posts per page.
11-20.
21-30.
31-40.
41-50. If it's past the first actual page, it's not worth it.
51-100.
101-200.
No limit. I'll join a topic conversation even when it's 10 posts away from 500.