Collisions should not be common enough to have chains (or skip patterns) of 20 elements, in an (unordered) hash map. It should be more like, one jump to the has

Collisions should not be common enough to have chains (or skip patterns) of 20 elements, in an (unordered) hash map. It should be more like, one jump to the hashed index, and then maybe another jump or two if there is a collision. That's significantly fewer jumps in memory than for a balanced ordered binary tree.