Nah, it just means that there is less stun on each move the longer the combo lasts. In CP it is like CT. In other words, based on time. Every move has a certain set value that shaves off the time you have left to combo, and there is a maximum limit that will end the combo no matter what combination you use.
In CS1, CS2 and EX, on the other hand, it was not time based but just based on certain moves, so you could keep combos going practically forever.