Agree, it's easy to be lulled into a false sense of security and let your guard down when flying with someone good/experienced.
I have to consciously remind myself to try and look at everything from the point of view of a 10 hour student when I am instructing ab-initio, having been caught out on a few occasions by assuming a student has learned/experienced something that they haven't. Was teaching circuits to a low hours stude on a fairly short runway one day. The guy lands long for a touch and go, applies power, and rolls with enough distance remaining to get airborne again, but without too much margin. Vr comes and goes, the end of the runway gets bigger in the windscreen, I call 'rotate'. Nothing. Pause. 'ROTATE'. Nothing. 'I have control', get airborne just as the far-end numbers disappear under the wheels. Climbing out I ask the guy why he didn't get airborne when I prompted him. Blank look from student: "What does 'rotate' mean?" he asks. Fair point. An expression we use every day, but one unfamiliar to a bloke with 6 hours flying experience who'd only been in aviation for a couple of months. My fault. 'I learned about flying from that'
ST