Even if they bring an 8 second rule in, refs will just interpret the actions of the keeper, so if they go to ground its 5 seconds on the ground, then another 5 getting up then another 5 or 10 adjusting shorts and socks and boots, and then the six seconds to get rid of the ball, adding another two seconds will make little difference cos the refs are shisser.
Make it so if the keeper has the ball in hands for 8 seconds then the ball is returned to the opposing team in the centre circle. id do the same for throw ins, more than 15 seconds the throw goes the other way, that from the point the ball goes out. with multi ball there is no reason why they have to take so long, and a fifteen second rule rules out all the towel and shirt use to dry the ball before long throws. when teams are waiting 25 seconds for a full back to meander up the field to take a throw wasting a minute sometimes.