The rule says: "10,000 hours of deliberate play are required to achieve mastery". What exactly is deliberate play? Erikson argued that it is not enough to simply use a skill many times. It's how you practice that determines whether or not you reach a high level. There are certain quality components :
- Breaking skills down into smaller skills and developing them
- Continuously develop the skill at a more and more complex level
- To be attentive and aware of feedback on your mistakes and to maintain the intention to keep moving towards excellence
It becomes very clear what deliberate play is, which is a painstaking effort to analyse a skill in detail and to master every part of it.
These tips work well for learning a tune, but what about poker? In poker, there is no such thing as practice. You can only sort of show off (unless you're playing with fake money). A pianist can rehearse his performance hundreds of times before a recital in the Carnegie Hall, but it is impossible for a player to try to take a shot at Jungleman unless he is really playing against him. Or is it still possible?
This question has long tormented me. What is practice in a game where everything is your performance? Is poker perhaps an exception to traditional ideas of mastery? I finally came to the conclusion that although poker has some nuances that are unique to it, the other rules should apply as in any other field. Poker has only inherent additions in terms of deliberate practice, such as learning or watching videos (we have discussed this before). But this is not enough. 
The only action that will obviously help improve your results is deliberate play. Playing poker is practice. Every session in which you play by focusing on your mistakes and trying to learn from them, in which you actively strengthen your weaknesses (e.g. taking more risks, playing more conservatively, or learning to play deepstacked), that is a deliberate session.
So it's not enough to grind for 10 000 hours. It has to be an active game. You need to hear the feedback coming from poker and use it to make changes to your game. If you want each session to get you closer to your goal, it has to be conscious, intelligent, with a measured effort to track and improve your weaknesses. Of all the players who jump quickly over the limits, I have seen only two types: the first "invest" a lot of hours in a short period of time, the second are very stubborn to improve and track their skills. Experience and stubbornness are the only viable paths to mastery.
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