The whole purpose of simplifying VFR naviagation by using SCA is to avoid having to use a whizz-wheel in flight or spend time 'head-in' looking at tables. In our crowded airspace we really don't need pilots fumbling about with the whizz-wheel when they should be looking where they're going - and all SCA work can be done head-out.
What is a 'ETI' check?
We don't require pilots to 'check' their GS, just to correct their ETAs. Hence proportional navigation is the most usual technique. Selecting such a suitable visual fix is rarely a problem - although I concede that it might be in the GAFA!