How many 10K hours do you have left?

This is a cool brain hack in that it uses math to convince you that you're not too old to become a master at something.

One issue I have with the 10,000 hour rule in general is this: there are approximately 2,088 hours in a work-year not counting overtime. To achieve mastery in your profession would then take less than 5 years. Most professions don't consider someone an expert 5 years into their careers. So does that mean a) you're not really improving that much in those 5 years b) there are more conditions to the 10,000 hour rule c) the 10,000 hour rule is flawed or d) the evaluation of one's expertise is flawed?

Another issue I have with the 10,000 hour rule is the idea of competence and sufficient experience. At what level of experience (in this case, hours) are you competent enough to achieve your goal? If programming, at what level can you create something that solves a given problem. If business, at what level can you successfully run a startup, etc.

So if the target changes to "enough experience to achieve a specific goal" then I'd argue one has much more time available to him/her than what this math suggests.

Anecdotal data, admittedly not perfectly analogous.

I got serious about playing the game of go relatively late in life for a go player--I was 23 years old at the time. In 2 years of hard study (1~2h/day, and a bit more on weekends) I rose from essentially a complete beginner to dan level play. Since then, life has pulled me away from playing go as actively, but the work I do at this point does let me maintain my level of play.

I think it's fair to say that you get MORE out of your effort at a younger age, but at the same time, I think that if you're serious about learning and honest about the way you learn, you can absolutely get a LOT out of those hours--and that ultimately, you can get the same utility as you would have, by tailoring your studies to the way you learn more effectively.

Yes but if you work full time and you have a family this 2 hours per day become rare. It's also important to notice that your body require to have some relaxing time which is also needed to be in consideration. Yes you may remove all "wasted time" of your day, but at the end, your brain will need rest. Spending your whole life optimizing this time will just get you more chance to get a burnout. 18 hours per week on free time is huge and hard to get once you have children, friends, and social activities.

Agreed.

I think this is where you get into mastery vs. experience. 10k hours of a task does not make you an expert unless you've spent those 10k hours deliberately attempting to gain expertise.

This is also where you get into good practice vs. bad practice. i.e., the average golf enthusiast "practices" by going to the driving range, because it's easy and fun and he's probably already decent at using a driver. Someone who wants to become a golf professional practices by hitting a hundred balls out of a sand trap or driving into the wind or any number of other difficult techniques they're not good at yet.

It's not so much the passage of time (10k hours) that matters, as it is how you spend those hours.

To your second point, "mastery" is sort of a vague term. I like your idea of "enough to achieve a certain goal". That's probably better from a mental health perspective too (experts in many fields are pretty crazy because they've devoted themselves exclusively to this one narrow area for years and years).

Also, most people aren't doing only one thing while they're at work.