What I said in a previous post, which most people have ignored, is that when calculating the viability and economy of repairs from an insurers perspective, the costs for the engine damage will almost certainly be excluded. There is no coverage for a mechanical failure.
Insurers will only be paying for the airframe and associated repairs. Therefore, now there has been a physical inspection of the damage, the numbers probably add up.
In general what you're saying is not at all correct, at least not in the aviation industry.
Aviation hull insurance contracts (unlike most types of insurance contracts) are written to a pre-determined "Agreed Value". Any payout resulting from an accident will be in this amount minus deductibles. That's it, no more, no less.
So in aviation hull insurance, the payout value is fixed, and the insurance company doesn't "adjust" the amount based on investigation into engine damage, mechanical failure, etc. The only value to determine is if repairs are economical (that is, under the Agreed Value). If not, the Agreed Value is paid out in full. Period.
In almost all instances, the value of the engines are covered as part of this "Agreed Value" under the aircraft's hull insurance.
The only exceptions relate to things like replacement engines, spare engines, and engines taken off the aircraft for maintenance, storage, shipping, etc.