Hey Julian, great questions! Apologies for the late reply, I’ve been out for the last two weeks.
1. Mirroring UV’s is not as common as I thought when I first made this course. It saves a lot of space, but does have a couple downsides when it comes to texturing – it’ll flip any text and will not work well with Substance’s tri-planar mapping. Neither of those are deal breakers for a project like this, but it’s good to be aware of. I’ll still mirror UV’s pretty often when I know those won’t be an issue, but nobody will correct you if you decide not to.
2. Blender’s packing leaves a lot to be desired, and wastes a lot of space. For an automatic solution I’d recommend something like Shotpacker (no 2.8 support yet though). Average island scaling works great for things that should have a uniform texel density, but some areas of the pistol (like the bottom) just don’t need to be as detailed as others. By scaling that down and scaling the more important areas up (the part that’s right in front of the camera) manually, you can pack more apparent detail into the same size texture.
3. Yes! If you don’t mark sharp edges as a seam and bake the normals so that they appear beveled (either baking from a high poly or by using 2.8’s bevel shader), you’ll get a nasty artifact. You can see why in this video: https://cgcookie.com/lesson/sharp-edges-and-uv-seams
Hope that helps, and happy modeling!
