It is incredible that Adam Sandler is one of the highest drawing box office revenue actors of all time. He speaks to a group of movie fans that love bad comedy, and not in an ironic sense, they genuinely love it.
I think that for Billy Madison, Happy Gilmore, The Wedding Singer, and the Water Boy he made some great absurdist comedy. However, those were all the same movie, with the primary difference being the lead character suffering mental retardation in varying degrees (e.g. Water Boy = severely retarded). Oh, and The Week Of (on Netflix) was surprisingly good too. Or maybe it was just not horrible, and coupled with zero expectations made it seem better than it was.
Largely, he never shifted into a gear higher than the first four movies mentioned above. All but one of his attempts to differ from his original formula have been disastrous (IMO). And Water Boy was made in November, 1998, the last of his
idiot rises above his apparent abilities, but gets the girl films*. Even if one likes 50 First Dates, which my mom adored, and believe The Week Of is decent, that's two watchable films in literally 20 years.
*Little Nicky is also this film, but is truly an awful movie.