This is super common in my experience. Senior/experienced devs spend a bunch of time ramping up the inexperienced or new members of the team and don't have much time remaining to work on their own initiatives.
We've tried to make it easier to turn organic code explorations into interactive docs that can be read many times over with a notebook-like feature. Here's a notebook that bobheadxi wrote up after he noticed he was explaining Sourcegraph's authz model for the billionth time: https://sourcegraph.com/notebooks/Tm90ZWJvb2s6NTc0
Patrick McKenzie has a good take on this along the lines of "teach someone to fish" (s/fish/code search/): https://mobile.twitter.com/patio11/status/108611151367121715...
We've tried to make it easier to turn organic code explorations into interactive docs that can be read many times over with a notebook-like feature. Here's a notebook that bobheadxi wrote up after he noticed he was explaining Sourcegraph's authz model for the billionth time: https://sourcegraph.com/notebooks/Tm90ZWJvb2s6NTc0