
Flipping this back is trickier than it sounds. It is a 2 turns process, because before the round ends, you must always draw 1 card. Unless you get a weakness, "after the round ends" will already had passed a process of drawing 1 card.
The only kind of round you can flip back is that you must first start the round at 1 card, use it up somehow in treachery test or inside your turn, then draw a new one to 1 card right before the end of round. (= Did not have 2 or more cards at any point.)
- First you must find a turn where you can dump an entire hand of X cards (X > 1) to 0. Before this round ends, you will draw one card. If not getting a weakness, making this round's hand count : 1 min X max, therefore you cannot flip back in this "dump turn".
- The next turn, you begin with 1 card you just draw. You must also find a way to dump this card away, making your hand 0 once again. Before this round ends, you will draw one card. Making this round 0 min 1 max, then you can flip it because both are less than 2.
- Supposed that you failed to use this 1 card on this turn (no eligible test to commit, the cost is high, Fast criteria not quite right, etc.) the end round draw will make your hand 1 + 1 = 2 cards. When this happen, you must start the process all over again, trying to zero out the hand on the next turn, then try again to zero out the 1 new card on the next next turn.
In other words, "if your hand did not have 2 or more cards" can be interpreted as : "You must make your hand 0 card at the end of turn, for 2 consecutive rounds."