Making the same mistake

It's been taught over and over again, from young till now, from parents to teachers. That we should 'learn from past mistakes'.

 

4 years ago, I made an error and it wasted at least 2 years of my time. Logically, such a mistake should have a significant impact on me, and you will guess I probably learnt my lesson. But turn the clock to recent, I think I'm moving on to making the same error.

 

Alas. How do you tell yourself to learn?