That experienced crews more frequently tend to use quick heuristics (not even yet available to the inexperienced newbie) which are mostly but not always correct is not a personal assumption but a finding from HF research, summarized e.g. in the following passage (for the medical field, but the same principle applies to the cockpit, too):
"(...) there is also evidence that as physicians gain experience and expertise, most problems are solved by some sort of pattern recognition process, either by recalling prior similar cases, attending to prototypical features, or other similar strategies. As Eva and Norman (ref) and Klein(ref) have emphasized, most of the time this pattern recognition serves the clinician well. However, it is during the times when it does not work, whether because of lack of knowledge or because of the inherent shortcomings of heuristic problem solving, that overconfidence may occur."
(Eta S. Berner, & Mark L. Graber, 2008: Overconfidence as a Cause of Diagnostic Error in Medicine. The American Journal of Medicine, Vol 121 (5A), S2–S23)
Taking the British Midland Flight 92 (Kegworth) accident as an illustration: the smell of smoke prompted the captain who was experienced with the 737 to quickly identify the right engine as the malfunctioning one (which was a wrong clue owing to Boeing's redesign of the bleed air system). An inexperienced crew without that readily available in-depth knowledge about the 737 would not have had any quick clue for heuristic thinking and would therefore have had to more slowly and meticulously analyze the problem (e.g., by looking at the small and apparently not too clear vibration indicators).
This does not contradict the assertion that the heuristics used by inexperienced crews are usually less accurate and often overlook important aspects that experienced crews are aware of, leading to "jumping to wrong conclusions" more frequently.