Like any major, the US Open has 4 rounds of Golf. The cut is made after 2 rounds. This year's tournament has been plagued by bad weather; so the second round is being played on Saturday, instead of the usual Friday.
mike weir
As of the 2008 Masters, that would be Tiger Woods with a 70.85 average for 46 rounds. Phil Mickelson is second with a 70.98 average for 54 rounds. They are the only two players with 25 or more rounds who average under 71. Click on the 'Masters Scoring Average' link below to see more concerning scoring average at the Masters.
4 rounds of 72, 288.
Tiger woods
He played all 4 rounds in the 1995 Masters where he finished in a tie for 41st and as low amateur.
Rory Macilroy
jack nicklaus
greg norman
7 rounds
infinite number of rounds
10 rounds
There are up to 40 rounds.