By adding extra turbines to any large dam regular Hydro is effectively self filling pumped storage. The losses end up roughly identical and you can release at the maximum or minimum rate at any point over a week as long as the total stays the same it’s almost free peaking production. The only issue is it’s location dependent and thus can’t scale.

This is why retrofitted dams generally increase the maximum power production rate even if the average remains the same time shifted power is extremely valuable.