Wow that sign is extra ridiculous. I think most people would struggle to read it standing right in front of it let alone driving past.

s316 does give a lot of leeway e.g.

(b) the sign has additional information on or with it; or

(e) the sign is combined on a single panel with 1 or more other traffic signs; or

The point where it becomes substantially different is pretty subjective, which IMO shouldn't be a thing when you're talking about road rules, but it's sadly not the only example.