Is it time to start calling out bad cyclists?

Interesting. But (from reading the article), doesn't that mean they can still enforce it under conditions, where it's dangerous etc? So how will that work, how as a cyclist will I know where I can choose not to use the cycle lane, and where I have to?

At least it's a step up from mandatory cycle lanes everywhere.

If all mandatory paths were fitted with the correct signs, and all non-mandatory paths did not have signs, you'd be able to tell by the presence or absence of signs. However, German local authorities are way behind on this. As the court judgement states, the requirement for them to only fit such signs in exceptional cases has in fact been in place since 1997, but they haven't complied. The new(ish) judgement now makes it crystal clear that they have to.

In the meantime, even cycle paths which do not present exceptional cases but which continue to be fitted with the signs are still mandatory until the authority has complied with the court judgement. I also think you can still be fined by police for not using such a path, although I would hope that police would use common sense if the Verwaltungsverzug (administrative delay in re-designating the path and removing the signs) by the local authority was pointed out to them.