mkdir -p throws no errors
mkdir throws errors if you try to create a directory that already exists.
mkdir -p is cool with not creating and not throwing an error if you try to create a dir that already exists.
From the man page:
On the other hand, with this option specified, no error will be reported if a directory given as an operand already exists.
That feels a lot better than
if [ ! -f myDir ]; then mkdir myDir end; fi