Most of the PR is passed through a 301 redirect, but there is a small leakage factor. If you’re just doing one or two redirects, this won’t matter; it is there to stop webbies from setting up a redirect circle to build infinite PR.
Ideally, it should pass the PR if done in phases. If you are setting up a redirect from site A to site B today and site B to site C tomorrow… It won’t work out.
If PR has already passed from Site A to Site B and then you are redirecting it to site C, it should pass the PR.
Long story but a few years ago all content was duplicated over 7 websites to provide better user experience (each site would have a ton of content)
Well the URLs on one site (B) were rewritten (C).
Now we are closing down some other properties (A) but there are literally a million pages so trying to figure out which old URL should go to the newly rewritten URL would be impossible.
Rather we are going to be redirecting the Duplicate URLs (A) to their match (B) which is now rewritten.