Be careful not to 'over-complicate' or 'over-normalize' your relational diagram. Keep in mind that the more "junction" type tables you create (such as those tables with only 2 id fields), the more tables you have to link into each query/form/subform to return/update the data (which usually means additional subform complexity/longer query returns). It looks like your last diagram compared to the first few is tending to overnormalizing the structure. This may or may not be a necessity. I usually avoid tables which ONLY hold 2 ID fields (unless it's a necessity). This tends to complicate coding and form design where it would've been easier to simply keep the foreign key ID in one of the other tables versus creating a separate 'intermediate' table which only holds 2 id fields.

Without knowing the details of your requirements though, I can't say if this is something you should/should not do. I just usually avoid tables with just 2 id fields (unless again, the requirements dictate the absolute need of doing so.)

It's very easy to over-normalize which is not necessarily good. The more 'separate' joining tables you have, the more complex the form/subform design will be.