Does interlinking hubs directly help organic traffic or indirectly?

It helps as your link is "do follow", and google will use it and the keywords that you are linking from to evaluate the hub you are linking to. So it will help.

I would be if the increase of 25- 50% is because of google increased traffic. But again it could also help that some on finds one of your hubs and because of the inter-linkinging moves to the next, there for with total increase and browsing between your hubs.

Bileygur hit the nail on the head I believe. My traffic to increased when I started linking my hub together as well as to other people hubs that are relevant to my hubs as well.

It is all about information for the searcher.

I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.