Where are you getting your information?
While there are good general rules of thumb, each joint must be analyzed to determine if the proposed design is adequate. Joints under tension will need much more scrutiny. Even many compression joints may become tension joints under a significant racking condition. I don't know what you are building. If anything more than a small shed, or sawmill shed, I'd highly advise working with an engineer experienced in timber framing, that will do a proper force and stress analysis. The rules of thumb are a good starting point, but no one on here can really determine if a joint is sufficient without knowing all of the loads and conditions.
I will say that in your tie beam to post example, I prefer a shouldered Mortise and tenon, which increases resistance to vertical shear, compression of tenon, and reduce twisting. Mortise can be full depth of post, or just shy of that. If you haven't read Steve Chappell's book "A timber framer's workshop", I recommend reading it. Despite the thoroughness of his explanations of the engineering, I still recommend an engineer on anything but the most straight forward small structure. It's very little cost compared to that of the building and the potential cost of a failure.