Do you link your money websites between them?

Hello guys!
Got this question from many months and never had any reasonable answer.
I got some "money website" in a different niche, some of them are good ranked, other ones not.
Do you think it's useful to use your good ranking websites to help others to rank faster? How, homepage links? internal linking? guest posts?

Share your opinions, please

1) if it’s in same niche why not
2) if it’s in a broad niche and can fit yes
3) if it’s a totally different niche no
4) internal linking for all sites recommended

I had the same question:
https://www.blackhatworld.com/seo/websites-cross-linking-good-or-bad-for-seo.1272305/

You can do this if it's worth. But consider that the more links that go back and forth the worst
Personally, I prefer all my money sites in different IP and unidirectional linking tracking all link directions in a document to avoid bi-directionality.

Nevertheless some blog networks with bidirectionality have success, most with a massive reputation. There was an example 3 years ago, from a popular BN like IGN that introduced a new blog about films and they started ranking with the top tier blogs in the niche in less than a year, thanks to the interlinking from their blog network.

But personally, I'm more into the web pyramidal schemes.