With a dry diet, I'd think it's normal to have at least one poop a
day. There's a lot in a dry diet that's unusable. A dry diet can
cause constipation, or can lead to conditions that cause
constipation. My rule of thumb is that if something is going on that
causes me to wonder if something's wrong, off to the vet. Cats are
too stoic, so we have to take tiny clues sometimes. Something like
not eliminating properly is cause for concern for me.