Do you want to focus on planning or progress?
Planning mindset:
"We did not complete everything as planned."
Progress mindset:
"Did we make as much progress as possible towards our goals?"
Two very different perspectives we must not confuse with each other. Except we frequently do.
We often conflate the inability to forecast with the inability to deliver, with disastrous results.
When you focus on your inability to plan, you will bump into walls. At some point, you can no longer improve your forecasts and will be stirring in noise.
When you focus on your ability to deliver, your forecasts will improve, and you will make the most progress you can.
Resist the urge to continuously improve your forecasts through better planning. You will experience diminishing returns quickly.
When delivery doesn't go as planned. First make sure you are delivering smoothly.
If you're not delivering smoothly, any forecast you’ll make is guaranteed to be a bumpy ride.
Saw an interview with Demming once where he said something like: "you can't get reliable forecasts from an unpredictable system, and a predictable system is predictable so you don't need forecasts." Of course more in the context of manufacturing, but I liked the Cruijffian wisdom.