I think one of the major misunderstandings of the 10,000 rule.... is that the 10,000 hours much actually be involved in directed practice. Most of the people that I know that go to Pool Halls and play pool, spend very little time practicing. If you are playing with someone else, you cut your practice time in more than half (usually). Playing at a tournament for six hours, probably doesn't really count for six total hours because much of that time is probably spent waiting between matches, etc......
I think a great way to practice is to decide on a specific number of balls that you will make during a practice session. You don't have to count misses at all.... Just count how many balls you pocket...