I put some 300-500 hours in S.A if not more. and I only put 30 in 4. because there isn't nearly as much to do there
it was just infact. less of a game than San andreas in every measurable way except graphics. and it has less character than vice city as it was merely a generic photorealistic looking game.
San Andreas had a bigger map, but there wasn't that much more to do. After 100 hours San Andreas, you also have seen and done everything... don't know what you did the additional 200 - 400 hours without feeling repetitive gameplay.
If you include GTA IV's DLCs (Episodes of Liberty City), the main story part is even much bigger than the main story of San Andreas: https://howlongtobeat.com/