Thanks Dennis, I understand that the size of the eye does not affect holding. Not overthinking - keeping it simple. Since we splice our own, I like to make them sized to the boat cleat. If oversized, there is a greater chance of them slipping off - especially when the boat shifts with tide or wake.
I know some prefer to put the eye on the dock cleat and adjust the length at the boat end. We often dock short handed so I prefer to adjust at dock end.