If you ever go in an area that allows 4, then you're allowed to have 4 for the day if you catch them all, or just 3 and 4 in that area. Just be sure that you can prove where they were retained especially if you move out of that area and into one with only 2 retention. We don't need to discuss the ease at which someone could take advantage of this silly system. It's pretty clear in my eyes.