Joshimuz found the first instance of mission duplication, followed by Cyberthunder, both by using girlfriend phonecalls (which isn't used in runs). S also started Quarry with om0 once in practice.
This wasn't understood until Tyriounet who accidentally started Quarry with om0, by that point we had already found duping in III and VC so we knew what it meant and immediately started testing. RunnerHAWORTH and Powdinet tested Quarry duping and it is now used in 100%.
A few months passed and Patrick found that by pause buffering, he could get phonecalls during the fades for certain missions like Trucking. This is the method that is used in Any%, though it has obviously evolved a lot since then.
The GTA:SA community has been deteriorating over a long period of time. Many top runners are not currently present on the leaderboard. This issue has not been seriously addressed yet, but an attempt will be made to remedy it now.
As of this news post, the San Andreas leaderboard will function in
