From the time Vito is shot the time he comes home from the hospital, Fredo is kept out of the loop as to what is going on with the mob war. He isnt in the room when Michael comes up with the plan to shoot Sollozzo and McCluskey, he isnt there while they are waiting around to find out where Sollozzo is taking Michael for dinner, and he isn't even there to say goodbye to Michael. Obviously both Sonny and Tom knew he was pretty worthless, but I wonder if even then they completely trusted him even then. By the time Michael gets back from Sicily, everyone knows that Moe Green slaps him around in public and Michael learns that he bangs cocktail waitresses two at a time. Michael also knows that Fredo had a tendency to take sides with paople against the family. All of this leads me to the question as to whether or not Michael should have kept a better eye on Fredo...even to the point of having him followed.
Had he done so the meeting with Johnny Ola in Beverly Hills, and Fredo's prior trip to Cuba and the Superman show would have been known to Michael, and it would have saved him a lot of trouble.
I am wondering if this was a lapse on Michael's part.