A race to 15 isn't that long. They could easily play that in one day. It's not like an ahead set or anything. I've played two races to 9 in one day, and also 3 races to 6. Neither day took longer than 10-12 hours I'm pretty sure.
Now if you were to say Varner vs. Walden, race to 15... That might take awhile.
with $50K on line, i am inclined to bet that at least have of those games, all balls will be up table, and at least 2 hrs to finish each of them, that is 16 hours minimum for those 8 games, even with best power one pocket players, Efren does not care he will push all balls up table and he knows he will win most of those games for sure. Long race in one pocket brings in additional factor to the game and that is Odds and percentages play; he who can manage those well will eventually win