I didn't really need to use that and it was still quite easy to keep going indefinitely.
Personally, I think that the only way to have a natural end to the game would be to make the speed up automatic every x points as well as optional.
Maybe even a penalty of some kind for clicking somewhere that there is not a shape. At the end I was just clicking constantly and moving the mouse up and down. If I used an autoclicker, I am sure that I could leave the game running all night.