Kees
Funny you mention this aspect. I went through quite some head scratching when designing my kitchen. Chamfering the inside edges of rails and styles asks for some planning. Here is what I would call, the IKEA solution (nothing bad about IKEA, it's just an easy and cheap method that doesn't look so hot).

And this is a more traditional aproach with unequal shoulders. The outside shoulder is different from the inside to accomodate the chamfer.

This method was very time consuming. I think there are special routerbits for work like this so it isn't handtool specific. When working with moulded edges there are similar solutions.

Otherwise, thanks for your explanations. Lots to think about.