Winding VSF AT WT

How much should I manually wind my watch? I have only been winding it 5-6 turns in the morning assuming the autowinder would maintain it. But it was losing 12s/d. So I tried winding it 25 turns this morning and now 18 hours later it is +2s when compared to atomic clock. So what gives? Doesn't the autowinder work? Why do I have to manually wind it? I don't understand.