FO OF A B767-300 BELIEVES THAT THE MANY CHANGES TO THE RWY AND ASSOCIATED STAR ARRS AT LAX ARPT SHOULD BE ELIMINATED SINCE IT MAKES IT HARD FOR FLCS TO REPROGRAM THEIR FLT COMPUTERS IN TIME FOR THE NEXT STAR FIX.

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OUR FLT WAS FROM JFK ARPT IN NEW YORK TO LAX. WE WERE FILED FOR THE CIVET ARR AND THEN TOLD TO EXPECT THE MITTS 1 ARR. BOTH THE CAPT AND I WERE FAMILIAR WITH LAX AND WERE EXPECTING THE TRANSITION TO THE MITTS ARR. WE HAD IT PROGRAMMED IN RTE 2 OF THE FMS. THIS WAS VERY HELPFUL FOR THE LAST MIN CHANGES. THE PROB BEGAN WITH 2 ACFT OF SIMILAR CALL SIGNS. THE 2 CALL SIGNS WERE FOR EXAMPLE FLT #XX AND #YX RESPECTIVELY. THERE CAME A TIME BECAUSE OF THE FREQ CONGESTION AND GENERAL HECTIC NATURE OF ARR INTO LAX; I WAS COMPLETELY UNSURE OF WHAT WE WERE SUPPOSED TO BE DOING. THIS LASTED FOR APPROX 2 MINS. A CLRNC FROM ATC WAS UNCLR BOTH IN WHAT WE WERE SUPPOSED TO DO AND WHICH ACFT THE XMISSION WAS FOR. I WAS UNABLE TO CONFIRM ANY CLRNC ON THE RADIO DUE TO EXTREME FREQ CONGESTION. WE ARE ALWAYS TOLD TO CONFIRM CONFUSING CLRNCS; BUT WITH SUCH BUSY RADIO FREQS THIS IS EASIER SAID THAN DONE. ON THIS FLT; I DO NOT BELIEVE WE WERE IN VIOLATION OF ANYTHING. HOWEVER; THAT WAS ONLY LUCK. THE NEXT CREW MAY BE UNFAMILIAR; OR NOT AS FORTUNATE. FLYING STAR ARRS INTO LAX IS ALWAYS UNNECESSARILY HECTIC. THE PLAN DURING ARR IS LIKELY TO CHANGE MANY TIMES FOR LNDG AT LAX. THE FILED STAR ARR IS OFTEN CHANGED AT THE LAST MIN. THE EXPECTED LNDG RWY IS OFTEN CHANGED; TOO. I CANNOT UNDERSTAND WHY THIS WOULD BE NECESSARY. ALL OF THE CHANGES MAKE OUR PRIMARY RESPONSIBILITIES OF FLYING THE ACFT AND LOOKING FOR TFC EXTREMELY DIFFICULT. SOMETIMES I FEEL THE CTLRS ARE NOT AWARE OF THE STRAIN THE CONSTANT UNEXPECTED CHANGES PUT ON PLTS. THIS PROB HAS BEEN LONG-STANDING IN LOS ANGELES. I CAN ONLY SAY TRYING TO MINIMIZE ALL OF THE CHANGES WOULD BE EXTREMELY HELPFUL.