Do you know what happens when you have to send out graduation/going away party invitations, bridal shower invitations, and wedding invitations (featuring four different people) in one week?
You pass off the duty to the four people, not having a clue who ends up on the invite lists.
Then, do you know what happens when invited guests randomly stop you and say, "Oh, I haven't gotten back to (name one of the four) yet about (name the event). Let them know I will/will not be able to make it."?
The information makes it into your brain but gets lost in between "The nurse will call tomorrow to schedule open heart surgery" and "Mom, did you see me tag that kid out at home?!" and you are left clueless as to who will be where and when and you resort to guessing about numbers and praying those who got left off the lists you didn't check will still be your friends when the dust settles.