I want to drive to Destination A. My usual route takes 30 minutes.
You say you have a better, faster route that’ll just take 15 minutes.
I follow your directions, and it takes me 45 minutes to get to Destination A.
Did you do me a favor? Should I thank you?
Assuming there were no unusual and unexpected delays on the new route, I would be irked. Estimating the travel time and being off by a factor of 3 is… unacceptable.