Perhaps when you'd Rather play a Tactician (your hand is Tac, TM, TM) to aim for a mega-turn next turn rather than gaining four golds and having a one-colony turn next turn. Or, on a related note, when you would rather discard-for-benefit (Cellar, Warehouse, Secret Chamber) or trash for benefit (Salvager, Bishop, Upgrade, Remake, Remodel), possibly because the game is ending this turn and you don't have the draw power to draw the golds from the top of your deck.
Obviously, one answer is When golds would run out, and you don't want to end the game yet.
Hmm, just looked at your answer. I guess it's sort of like the first thing I said, but without the Tactician since your deck is good enough without it.