Being open to new ideas and new knowledge is what is needed to learn. Experimenting, seeking out new knowledge is even better.
You can be successful and see an even better way to do things and learn from it. This seems the best way to learn to me – not to just learn from mistakes. Of course this means your goal has to be improvement not just avoiding more mistakes than before.
Your actions are based on theories (often unconsciously): and learning involves improving those theories. Learning requires updating faulty ideas (or learning new ideas – in which case ignorance rather than a faulty theory may have lead to the mistake). Encouraging people to learn from mistakes is useful when it is about freeing them to make errors and learn from them. But you should be learning all the time – not just when you make mistakes.
You can be also be wrong and not learn (lots of people seem to do this). This is by far the biggest state I see. It isn’t an absence of people making mistakes (including carrying out processes based on faulty theories) that is slowing learning. People are very reluctant to make errors of commission (and errors of commission due to a change is avoided even more). This reluctance obviously makes learning (and improvement) more difficult. And the reluctance is often enhanced by fear created by the management system.
It is best to be open and seek out new knowledge and learn that way as much as possible. Now, you should also not be scared to be wrong. Taking the right risks is important to improving – encouraging creativity and innovation and risk taking is wise.
Experiment and be open to learn from what could be better and improve (PDSA is a great way to try things and evaluate how they work). And the idea is not to be so conservative that every turn of the PDSA cycle has no failures. In order to get significant successes it is likely you will try things that don’t always work.
The desire to improve understanding (and the desire to improve results provides focus to the learning) is what is valuable in learning – not being wrong. Creating a culture where being wrong needs to be avoided harms learning because people avoid risk and seek to distance themselves from failure instead of experimenting and digging into the details when something goes wrong. Instead of learning from mistakes people try to stay as far away from them and hide them from others. That is not helpful. But what is needed is more desire to continually learn – learning from mistakes is wise but hardly the only way to learn.