fiber optic front sights
I shot in an informal club match on an indoor range last night.
We had a dozen shooters. Three of them had fiber optic front sights on their handguns. They discovered that there isn't enough ambient light on an indoor range for the fiber optic front sight to work properly. That's what they learned.
I relearned that if I try to go too fast and bash the trigger, the results aren't pretty. Fortunately, I only did that on the first stage and then I calmed down and shot better for the remainder of the match.
You can only learn from experience if you pay attention!