Monitoring is not done by subjective listening to engines or so. It is an instrument scan of the most important items on the pfd: speed, horizon, altitude and vertical speed. If any of these change in an unexpected way then something is wrong, and it should alert the pilot to take action. Other items are looked at too, but they are not so important as these 4 parameters.
The pilot responsible for scanning can do other things like handling a checklist with the other pilot. But he can never let himself get preoccupied with something else. His preoccupation is scanning. The sequence for him is: scan, flick a switch, scan, flick another switch, scan, etc... This is adequate enough to detect any anomalies in the trajectory in time. Where it goes wrong is that some pilots think they can work through something like a whole checklist without scanning once. Then a problem can develop for over a minute and longer. If only the Turkish pilots had done their job and scan, they would have immediately noticed the unexpected decay in airspeed and the unusual pitch up, instead of letting it develop unnoticed for over a minute.
The trim wheel is (almost) never used. There is a switch on the yoke to drive that thing electrically. When used, the trim wheel starts to spin and make a loud clicking/rattling noise. So when the autopilot uses excessive trim, you will notice that immediately too. There is no issue with electrical trim being slow. If you watch the trim wheel spinning you can see how fast it is.
Trim usage during take off:
https://www.youtube.com/watch?v=-X01uY0bJs0The leaks from the investigation are contradicting now. The first suggests a high energy climb and the second a stall (low energy). Though FR24 data is very unreliable in detail, it can point to a general tendency. It's data points to high energy climb. All in all there is not enough information and the wording of the articles does not make them sound very credible either. In a few weeks there will be some official data the investigators have said.
Kind regards, Vincent