Derek Carr has the most games with a completion percentage of 90.0 or above and 30+ passing attempts, with 2 games.

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who has the most games with 90 completion percentage with 30 attempts
Interpreted as:
Who has the most regular-season games with 90 or higher completion percentage with 30 or more passing attempts?
CarrBrees21
NAMEGPPCTATTCMPYDSAVGYDS/GTDTD%INTINT%SCKSCKYRATE
Derek CarrDerek Carr290.966606119.3305.534.511.517114.1
Drew BreesDrew Brees196.7302930710.2307.0413.300.000148.9
StatMuse has game-level data for completion percentage and passing attempts going back to the 1950 season.