Also communal RFCs, RFPs, Roadmapping, Architecture/Design Proposals, Design Docs and/or Reviews help socialize/diffuse org standards and expectations.

I found these help ground the mentorship and discussions between junior-senior devs. And so even for the enterprising aka proactive junior devs who might start working on something in advance of plans/roadmaps, by the time they present that work for review, if the work followed org architectural and design patterns, the review and acceptance process flows smoothly.

In my juinior days I was taught: if the org doesn't have a design or architectural SOP for the thing you're doing, find a couple of respectable RFCs from the internet, pick the three you like, and implement one. It's so much easier to stand on the shoulders of giants than to try and be the giant yourself.