Kill them, you must be joking. In a five set game of squash which has much longer rallies that is exactly the amount of time that used to given between sets.
In one of these “super fit tennis players have now been on court for nearly five hours” matches they will have played less than 30 minutes of actual tennis, seriously that is how long the ball is in play in such games.
In fact one survey in the US found that the ball was ‘in play’ for just over 16 % of the duration of a match.