You do if you used a new tactic for a problem the previous tactics did not work.
You kinda missed the point, though you were very close. Allow me to help you the rest of the way:
Q: Why did you come up with the new tactic?
A: Because the previous tactics did not work.
Conclusion: You suffered defeat before and as a result you were forced to come up with a new, better tactic.
Once you won, you didn't come up with new, better tactics because you didn't need to. Hence, you learned more from a defeat. Comprende?