~r, three mon~hs at her new job, Arizona s Sandra O Connor is working IO-hour days, lunching at her desk and has quickly become "one of the guys" on the U.S. Supreme Court. "Within the court itself, she has fit in very easily," Justice O'Connor's law clerk, Ruth V. McGregor, a Phoenix resident, said today. "On the world outside, though she is the first woman on the court' and that is historic." Mrs. McGregor, who was Justice O'Connor's hand-picked choice for the prestigious one-year clerkship, told JUSTICE O'CONNOR RUTH McGREGOR The Phoenix Gazette the new justice has not aligned herself with any philosophical group on the ninemember high court. "SHE ANALYZES each case individually and very carefully," said Mrs. McGregor, who was a partner in the Phoenix firm of Fennemore, Craig, von Ammon & Udall. In the 11 rulings already issued since Oct. 1, Justice O'Connor "has not lined up with the traditional liberal or traditional conservative bloc," Mrs. McGregor said. If there has been a surprise for the 38-year-old attorney, a 1974 graduate of Arizona State University College of Law, it has been the heavy workload. "Most Americans think that since the court is in session 14 weeks a year, and hand down about 160 decisions, that they don't work the rest of they year," she said. "Actually, the workload is incredible, and the justices work very long hours," Mrs. McGregor said . EACH WEEK, the court receives about 100 petitions for review, making for a three-foot-high stack of reading -