Did the cast know that season six was going to be the last?

I saw an interview with Jerry mathers a while back and he said that they knew because everyone decided that if they let the show go on any longer, they would just be repeating themselves because Beaver would just be doing all the things Wally did. Jerry also wanted to go to finish his high school years normally since he had been tutored on the set everyday, so he wasn't going to continue even if they wanted to keep the show running. I think they ended it at a good place.