No, you are correct, gelling occurs from the inside out. As the soap heats up from the inside it spreads concentrically outward, which is why it looks like a darker center on the inside with a ring of lighter soap on the outer edges.
You are less likely to get gel in individual molds than in loaf molds just because it can cool so much more quickly in the individual molds. Loaf molds have more soap volume to heat up and gel more easily. There are several factors that can contribute to or impede the heat required to ensure gel. The amount of liquid used, as well as other heat-producing ingredients in the formula, and of course the amount of heat used during and after the process of making the soap.
If you want full gel in your individual soap molds, depending on your formula, you will probably have to insulate them and even possibly use the CPOP method. If you don't care about gel for your individual molds, I wouldn't worry about it, because you are not likely to get a partial gel anyway.
But if you are doing larger volume molds, such as when you mentioned in another thread that you used a kitchen container and cut the soap into bars, then partial gel could happen if the circumstances contribute (more heat inside, but more cool outside the soap). That's when the formula and the amount of heat matter to prevent partial gel.
As to how to check for complete gel without cutting into the soap, I think it's more a matter of experience, sort of a trial and error as you get to know your formulas and how they behave in your circumstances over time. You are in the Phillipines, where I believe it is pretty warm most of the time, so I would expect you have a better chance of getting full gel with a loaf molded soap sitting out in your kitchen than I would in my cold winter kitchen. But again, it depends on various factors, such as amount of liquid in your formula, which oils (Coconut contributes to more heat) used, any sugar or alcohol content (milks, beer, etc.) and other additives.
When I was new I asked a similar question and was told the surface of gelled soap looks a bit more waxy than the surface of a non-gelled soap. That didn't compute well in my mind at the time, but I do see that now to be the case. For me it just took time and experience to learn with my own formulas and my particular environment.
