[Sombre]

Except it doesn't work like an ice cube tray. Dominion can jump over any province which has friendly dominion. It doesn't have to be full.

This can be observed easily by starting a new game with dom 10. You never have to wait for the dom in a province to reach 10 before it 'spills over' into the adjoining ones.

That said it is /more likely/ to spill over once provinces are at full dominion, because it has nowhere else to go.