I recognize that some players are doing this these days and they literally shift service pos before serve every pt
I dont think this is realistic becoz u can't "slide" to change service pos in real life.
Also, it is gamesmanship to throw opponent off (returners dunno where to position themselves to return serve because the default pos was supposed to be the correct pos if their opponent doesn't shift his pos.)
IMO, they should be banned...unless it is done on the 1st pt of the game. What do u think?