By George,
I agree with you in a sense. Knowing your aircraft and a commonsense check is great. But as you described, it doesn't always work.
As mentioned by someone, one rule of thumb was to use the speed achieved at the 1500' markers as a guide. Do they brief it? And brief what actions they are going to take if its not achieved? Perhaps their rule of thumb is different from the person sitting next to them. Wouldn't be worth much if they don't actively go about using it would it?
If it was as easy as using rules of thumbs, wouldn't the manufacturer provide this guidance? What quality control is there on them?
The only consistent way of trapping and mitigating error is a robust SOP with checks built into it. If these rules of thumb were so good I am sure the airline would add them to its SOP to improve safety.
Good on the crew for making the report.
The Don