Only if we change our way of working, the result may be different.
If we keep working the way we always did, we will keep making the same mistakes, and our results will be later than necessary. Because "hindsight is easy", we can often use it to reflect on what we did, in order to learn: Could we have avoided doing something that now, in hindsight, proves to be unnecessary or superfluous, or could we've done it more efficiently? Reflection, however, doesn't recover lost time: the time is already spent and can never be regained.
Foresight is less easy, but with foresight we can think that what we're going to do will prove to be unnecessary, superfluous, and decide not to do it, or that it can be done more efficiently, and hence save time.
Reflection is for hindsight is for learning. However, it is useless if we don't actively use what we learned for Preflection. Isn't it strange that we have a word 'reflection' but not a word 'preflection'? Only with preflection we can try to foresee, and thus prevent wasting precious time.
This is used in the Plan-Do-Check-Act or Deming cycle and it's one of the basics of Evolutionary Planning