You might, but the research is starting to become more and more clear that the "magic moment" is when you feel better.
We know that moment. At least, I do. When you're not really sick anymore but you're still recovering from the weakness left in the wake.
I have a group of doctors for an advanced immune system issue and this has been there advice for about four years. When I need antibiotics, we have top use the minimum dosage possible. So they tell me to stop when I feel better. And I do. I have bottles of half-full antibiotics in the bathroom drawer because of it.
My experience is only anecdotal, but I've never had to start over.