Thirty years ago Michael Porter wrote about how companies can gain competitive advantage through every part of the company, including HR. Excellent HR starts with its ability to recruit and retain talent, and appearing to have your act together goes a long way.
In other words, don't send an email telling an applicant they have advanced to the next round on Friday, followed by a flush email on Monday. It doesn't leave the best impression, and makes an applicant question the competency of the whole operation.
Little things can carry enormous weight.