For any realistic workload containing a mix of failed-lookups, and lookup-hits midway through the list, we're talking about many thousands of comparisons for a

For any realistic workload containing a mix of failed-lookups, and lookup-hits midway through the list, we're talking about many thousands of comparisons for a single lookup on average. Regardless, replace list with linked-list in the above example, for illustrative purposes. I agree that measurements & hard-data are preferable to guesswork, but it takes time and energy to gather these measurements and hard-data as well. For minor decisions where the alternative proposal is very slightly more complex, but there's a very compelling reason to assume order-of-magnitude performance improvements, I would argue that gathering data is a waste of time.