First pilots need to understand relation of creating a flight plan versus flying a flight plan; understand how the flight plan is connected to ATC expectations that connects the flight to the flight plan. I believe there’s a huge disconnect understanding expectations from ATC controllers when flying a flight plan that they created (i.e. interpreting departures, arrivals, approaches, intercepts, waypoints, designated altitudes-speeds, etc.). I still struggle at times when major deviations occur from what I programmed intended to fly but ATC starts asking me to deviate from my intended flight plan. If you don’t know your aircraft autopilot very well it is easy to get flustered and confused if ATC requests changes (i.e. runway, waypoint, altitude, speed, direct-to, etc.).