That's the key point, to get to the sideline. Referees are only expected to start the countdown once a player is deemed to be taking too long. I watch a lot of football and as far as I can see they are applying it correctly, but this does include an element of common sense. Classic example being for long throws, they are giving the attacking team time to get their defenders forward but it is still vastly faster than last season. Although granted 20 seconds is a long time and I'd expect at least a bit of encouragement from the referee to hurry up.From what i saw yesterday, epsecially as the game was drawing to a close, one team was taking longer and longer.
Sometimes it took a player over 20 seconds to get to the sideline to prepare for the throw.