What the plateau looks like in the field
It rarely looks like a problem. It looks like competence settling into routine.
The routes get familiar, so the drives start to feel the same. The talking points settle into a script that works well enough, so they stop being refined. The questions guests ask begin to feel predictable, so the answers get shorter.
Sometimes it shows up as a guide driving past something interesting. Not because they do not know what to say about it, but because they have not rehearsed it enough to feel sure it will land. A sighting that does not fit the usual script feels like a risk, so the vehicle keeps moving. The knowledge is there. What is missing is the confidence to use it, and that comes from practising out loud and hearing honest feedback.
The night sky shows the same thing. How many guides on your team can confidently point out more than three or four constellations, and tell a story about each one? The sky is above every guest on every night drive, but if a guide has never been pushed to practise it, it stays a gap that nobody notices.
Nothing is wrong, exactly. But nobody is watching closely enough to say that something has gone quiet, and the guide is too close to their own habits to notice it themselves.