Do we? Or do we all simply make assumptions based on little or no experience or first hand experience?
In my case my insurance companies have always acted in a professional and exemplary way. They have always repaired my vehicles immediately without any quibbles.
They have paid for all the legal costs involved in seeking personal damages etc and without any pressure from me.
In my last case they provided a free hire car whilst my car was at the repairers at no cost to me, even though it was not part of my policy. They simply recovered the cost from the other side.
They have always resisted all attempts by the other side to shift blame. They have always made sure that my No Claims Bonus was covered by the other side and that I suffered no loss of NCB.
I always have Fully Comprehensive insurance and so I do not get involved in personally fighting the other guys insurers by way of a third party claim. Let your own insurers do the work, it's what you pay for.