I'm not up to date on the state of the art but I've implemented hash tables a few times and we would expand the hash table whenever it was 75% full, which means x is never greater than 4. Improving the runtime from O(x) to O((log x)^2) doesn't matter when x is so small.

I imagine there are some niche memory-constrained applications where you'd let x get larger but I never ran into them personally.