I would have to say "NO"! However, if a player were to once reach world class level, and then get into other activities that make playing/practice a 3 days a week deal, then I think it's possible to do. But initially getting to world class speed takes too much for a working man. That said, I think it's more a lifestyle than actually time spent on a table. You need to be able and willing to play anybody, anywhere, anytime, and in some cases for anything. A working man would have to decline getting into a 10 ahead game of one pocket on a Sunday night for fear of risking not being able to make it to work Monday morning. I think it's more immersing yourself in the culture and state of mind than actually spending time on the table.
Example of skill -vs- knowing how to win:
I knew a young JR High school kid in Japan who is now a young pro on the JPBA tour. Hayato Hijikata. When in school, he came home from school and put at least 4 hours a night on the table doing the kind of drills that we all know we need to do but are sometimes too lazy to do???? On weekends, he played in tournaments. He was soon a higher level amateur player. Once he graduated from Jr High, he opted not to enter high school (high school is elective in Japan) and work on turning pro. So then his daily routine became practicing every day during the daytime, and playing in a tournament EVERY night. Weekends were reserved for larger events. In a very short period of time, he turned pro and was slowly becoming a threat to finish in the money in larger pro events. His skill level had not changed considerable from when he was in Jr. High. By that I mean athletically, what he could do with a pool cue hadn't taken a sudden turn for the better. However, he went from being a good amateur to a strong pro player just from playing in a competitive situation on a daily basis. He had learned how to win, and in some cases, he had learned not to loose. More state of mind than physical skills when you get to that level.
dave