[15a bottom] R’ Rosner explaining Tosephos: If a man knows that he is not the only one being relied upon, he is not going to be as careful, and might mess up. But, if someone knows that he/she is the only one being held responsible, that person will make sure to do it fully and ensure the job gets done properly.
D-E-ep Thoughts: When 11 men are in town, each one thinks that he can be the one not to show up at Shul for the Minyan, and no one ends up there. But when each person knows that there are only 10 men and there will not be a Minyan without him, then each man will give it his all to be there. If we simply switch our mentalities to think that we are always the ones who are going to ‘make it or break it,’ then all our efforts gain much greater chances of truly being successful.