Snapping lightmap UV shells to power of two grid?

When preparing assets for UE4 (in this case I’m going for the best baked lighting quality with the least amount of bleed)- would the best method of preparing the lightmap UV’s be the one shown in this excellent video? "Baked Lighting" and "Lightmaps" (Maya & Unreal Engine) - YouTube

The main thing that stuck out to me as being different from the other guides I have watched is that at 17:40, he begins snapping the UV’s to the grid, which is laid out in the same power of two dimensions that would be used in game. Would this be the most optimal way of getting the least amount of bleeding and distortion in game?

Also I saw this post about needing to subtract 2 pixels from your lightmap dimensions- is this really the case?

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I think, in post about 2 pixels, author talk about distance between UV patches. It must be equal or greater than 4 pixels. And you can snap UV vertex like in a video tutorial without problem.

Ah I see! Thanks for clearing that up!

With regards to the uv vertex snapping- is this the recommended way of creating lightmaps vs just laying the islands out undistorted with enough space? Since you are snapping the verts, you lose some the original island shape, so would this be problematic or would the benefits of snapping to grid outweigh the slight distortions?