Go back to 24.10 and listen. He explains that the Loops would cause problems unless you go through and alter the geometry. Creasing isn’t as intuitive as edge loops and can create some ugly results. Now to answer some of your question:
1. When to use? in most cases, it’s a matter of personal preferences. There are some cases like in the video where Edge loops creates ugly results unless you go in and adjust the geometry. Creasing can also be used to reduce geometry. Side note:In this case we are talking about edge creasing. In some cases to get good looking results you need to use vertex creasing or a combination of both. Vertex creasing was added to blender in 3.2 I believe. He is using 2.93 in the video.
2. Creating edge loops won’t create n-gons or trigons(Triangles). Basically supporting loops and creasing are 2 methods of sharping edges when using subsurf modifier. In some cases one will give better results then the other. In most cases either one will work fine.
3. Unfortunately there is no rule of thumb. It comes down to experimenting and seeing which gives you the best results. As you gain experience, you will develop an eye for when to use one over the other.(So I’ve been told. I haven’t developed this. So I guess I don’t have enough experience yet, but then again I mainly do rigging and TD work in Blender)
