I think that’s a good observation. I always felt like Holy Grail went downhill quite significantly after the first hour or so. Up until that point the narrative is fairly straightforward and the humour is consistent, but then they get to the animated montage time skip bit and everything after gets a bit boring. Most of the cast exits the film abruptly, the sets all look the same, and the ending undermines everything that happened up until that point. Which I guess is the joke, but The Life of Brian found a much better balance between satirical and absurdist humour and telling a cohesive story beginning to end.