The above number is the cost factor of making mistakes.
Don't get me wrong, mistakes equate to experience. And experience is very important.
But if possible, avoiding mistakes/moving in the wrong direction can save you 2.5 times the time.
Why? Here's an example:
Suppose I work on a task, like the one described in the previous post and it's something that the customer didn't want. It takes me 1 day to complete it.
The real cost of this is:
- 1 day to implement the unnecessary feature/mistake
- 1 day lost of not implementing required features
- 0.5 days of context switching and clean up
So it cost me 2.5 days.
In a sprint, that's a lot of time lost.
Now I must tell you not to have fear of doing anything in case it's wrong. This is not the point of this post. It's really about making you aware of the cost of doing the wrong thing, implementing an unnecessary feature, or working for too long without feedback from your customer.
How do you remove the fear? Always discuss what you're doing and how you're going with your customer.
This will help you stay on track and improve your development velocity.