When you look at skill levels, you have to know that it is only true for that manufacturer. Each uses only three skill classes. What is expert by one might be intermediate for another. The instruction, plans and design have a big affect on true skill level between companies. Another that has a large effect is the intended customer base the company is trying to capture.
Let me use Mantua as a example since I have built several of their models. Their intended customer base is the advanced modeler. They have their entry models but some of them should be considered advanced beginner because their instructions are limited. Their intermediate models cover another large area to fill in the gap before getting to their advanced models. Some of these I believe would considered advanced by some other companies. For example, their paddlewheeler, does not belong with their other intermediates, but when you look at rtheir advanced kits, it does not qualify for this class.
Using the "Le Soleil Royal" by Mantua that I am working on, their plans are decent enough to build the model, but they have inconsistancies between views and you have to figure out which dimension is correct by going to the ship and determining which is probably right. To decide what the end product of a part should be built like sometimes involves finding various components on three views and trying to determine what the intended outcome is supposed to be. Their instructions are ridiculous and can not be done in order described. The research was sketchy and there are way too many design flaws for a model of this level and cost. This and the "Soverign of the Seas", my next build, I feel, should be classified as Master level along with their "Vasa". However, when you finish one of their kits, it is exceptionally beautiful and well worth the effort and time involved.