This post says it takes a bit of work to create the dumps. It seems to me most of the work can be automated. Not sure what is the "bit of work" that takes two months to finish instead of one.
This meta question has a similar inquiry. Yet it was closed because 'supposedly' it was a duplicate. The other post was about why the torrent was incomplete. It wasn't about why creating the dump takes too much work. I don't see how it was a duplicate!
The whole issue has gaps in providing adequate explanations & information.