AFTER a fortnight of Christmas fiestas, Mexicans groggily returned to work two weeks ago. Or rather, most of them did. For the 500 deputies and 128 senators of the national Congress, the holidays roll on until February. Mexico’s lawmakers sit for only 195 days a year, the second-fewest among Latin America’s bigger countries. (Their $11,200-a-month pay, however, is the highest after Brazil’s.) When they do stir themselves to vote, it is more often to block rivals’ bills than to pass reforms.