No injury time outs whatsoever.
Either you CAN play and play till the end, or you CANT play and LEAVE THE F'king court and let the other player win it.
Injury, brainfart, muscle pain you name it, i dont buy it. If you cant continue playing in current conditions, when the time is up to go on the court, shake hands and let the more ready ( in that moment ) player win it. i dont care if you had to SHIT in the toilet between two sets, if you dont come to the court after regular 5minutes pause, your time is up and you LOSE. Period.
Simple as that.