I remember me and a friend tried to concisely put together a timeline for the series based solely on consistency, and all I could come up with was a three timeline setup, with certain games being catalysts to linear splits, and it didn't even encompass every game. The Sonic series has practically no consistency beyond the surface level, so I just don't even try to think about how one game matches up with another anymore, unless it's some direct sequel stuff, which to my knowledge has only happened twice (Sonic 2->Sonic 3 and Sonic Adventure 2->Shadow the Hedgehog (Heroes barely mattered in that series)).