"The most important single heuristic in my experience is that if two betsizes getting substantial use are clustered, picking one in the middle gets most of the EV. If they're separated more, using both ends up adding substantial EV." -Sauce

Does he mean clustered vs separated in how sizes are mixed within the individual hand or clustered as in how sizes are distributed throughout the range? Can someone please explain how I should be picturing this when looking at solver solutions?