@john456852 That depends on what kind of speed in chess games you perform best at. If you do best in fast time controls like G/45 rather than G/75 or (40/90 and SD/60), then I suggest you play in the 3-day part for optimal chances of doing well. If you do best in moderate time controls like G/75, then play in the 4-day part. Otherwise, play in the 5-day part.
For me, I am playing in the 3-day part (U2200 section) to be exact as playing in the 3-day part in the U2000 section in the World Open back in 2005 was the reason I did well (initially going 0-3 in the first 3 rounds of the 5-day part, but went 6-3 when I re-entered to play in the 3-day part).
there are always 9 games