My previous boat was a C25 with a swing keel and there was no single low spot. There are a couple of shallow recesses but as you say then are divided by ribs without limber holes. I did not have any leaks and had no bilge pump installed because I mostly trailer sailed it. When it was moored I would check to see if I had any water every time I went to the boat but that would just result in removing the cobwebs. If you have a section that collects water or just want an electric pump for emergencies, I would place it in the deepest section and any significant flow of water would overflow into it.
BTW there is no such thing as a bilge pump that "get out ALL the water". They all leave at least 1/2" of water under them.