GT1 - 1997
GT2 - 1999
GT3 - 2001
GT4 - 2004
GT5 - 2010
GT6 - 2013
GT Sport - 2017
They take twice as long to release a game one time and the stigma stays with them forever lol
And that's not even including prologues or the PSP game or anything.
How PD managed to make GT3 in 2 years (on a new hardware) is beyond incredible, I have no idea how they pulled that off.