Originally Posted by WhyFi

Are there pretty noticeable magnetic "slots" or is the whole slab fairly uniform?

I've got one long line of magnets end-to-end, nine of them, each about 2" long. The knives will stick anywhere but, as previously mentioned, it's certainly weaker when straddling magnets. I'm already thinking about another one, maybe with two parallel lines of the same magnets, separated by an inch or so and with the magnet gaps offset.