When do I reshuffle my discard pile: as soon as my draw deck is empty, or only when I need to draw?

Question

Accepted Answer

Only when you need to draw a card and the deck is empty. Emptying your deck by drawing your last card does not trigger a reshuffle, so a deck of exactly 4 cards stays empty until the next draw.

Watergate

When do I reshuffle my discard pile: as soon as my draw deck is empty, or only when I need to draw?