About 80% of the German tourist routes are 100% within Germany but 20% do cross borders. I don't wanna split a deutr system off which covers only 80% of the routes. Although I just did the very same for norntv which comprises only 95% of the Norwegian tourist routes.
You are thinking nationally here - splitting into countries. I'm thinking systemly here - splitting into systems.
The sctntr system (which obviously isn't gbrntr, covering the whole UK) has just the 12 national tourist routes (
1), and doesn't include many other routes (eg there's 17 routes mapped here
here: the 12 national routes, 3 of the 4 'road trip routes' (NC500 and copy-cats*), one of the several trails, and the one Scenic Route created out of an attempt to try and copy Norway, forgetting that routes already existed!). That's because the system is a system, rather than a grab-bag within a region.
The norntv system has
all the 'Norwegian Scenic Routes' / 'Nasjonale turistveger' in it - that there's another tourist route in Norway (there might be more - eg the
Blue Highway - but when I briefly looked, I couldn't see it signed) is neither here nor there as to whether it's a complete system.
A large number of routes would remain in the European grab bag (perhaps we have an active system, and a 'under-development' system, perhaps with specific review systems and just move stuff across for review and activation?), but these two are certainly systems in their own right - they could go back into eurtr, but they can stay out as coherent entities.
*Of course the NC500 is itself somewhat of a copy-cat, modelled after the Wild Atlantic Way. And I'm pretty sure the MR, GTS and WAW are interlinked. They kind of form a sort-of-system (certainly a subset of a grab-bag system) together - and so we might want them grouped together.
