Long shot, but it never hurts to try:

I've found myself wanting /usr/bin/yes to accept -d <int>, e.g.

  yes -d5 .

which would output '.' every 5 seconds.

Obviously, I can just use a shell loop and sleep(1) instead, but
that same argument applies to yes(1) as a whole. Nevertheless, it's
a beautiful little utility that I think could benefit from this
backwards-compatible enhancement.