I don't think I'd call along freeways "useless". Easy, yes, comparatively. But I'd say it's incredibly useful as trunk infrastructure.

But you're right, it's much less useful when not part of a proper connected network. I don't know of any studies into this, but that would be really interesting to see.

A couple of other things that frustrate me: when there is good trunk infrastructure, but it loses priority at intersections. I'm talking the North Brisbane Bikeway at Albion Rd & McDonald Rd/McDonald Rd & Blackmore St, where the Primary Cycle Route crosses a Neighbourhood Road, but the bikeway does not run continuously across that intersection. And on the Southwestern Freeway/Centenary Freeway bikeway when it crosses Witton Rd, where it has to give way to a small secondary road, and Fig Tree Pocket Rd, where it has to give way to both the on and off ramps of the highway, rather than going under or over the main road like the Gateway cycleway always does, or simply requiring cars to give way at a wombat crossing.