[Koningkrush]

I would just assume that defaults work both ways, but that isn't always the case.
For example, you can know Metallurgy at default from Chemistry-5, but you can't know Chemistry at default from Metallurgy-5.
I suppose I could just run down every single skill and look for any issues like this and create a list. It would just be a little time consuming.
I'll post it here if I do get around to doing it.