If five people share responsibility for a failure, how does that 100% get divided?  A true leader knows there is only one answer:

You - 100%
Person #2 - 100%
Person #3 - 100%
Person #4 - 100%
Person #5 - 100%

Each individual assuming 100% responsibility for the failure generates 100% effort to correct the problem and make it a success. Add it up and you get 5X the effort.  And by the way, less than 100% always seems to make it someone else's fault. Interesting how that works.