The ellipse technique is basically the tool that is being used to transfer that depth measurement to the vertical axis. It is entirely precise. While there are other techniques (which I'm not particularly well versed in, as they rely more on looking far back to the vanishing points and horizon line), they aren't any more precise than this. I think what's been confusing me about your statements is the implication that what we're doing here is somehow less precise.

Admittedly, working with a more limited set of ellipse guides would make this technique trickier to employ (since you need an ellipse that'll match the desired criteria) - but again, that comes down more to the tools at your disposal.

There's definitely more to be learned in regards to perspective - lots more tools that we don't get into here simply because we're focusing on things that occur physically close to the object we're drawing, rather than relying on far-off vanishing points that may be way off the page. Scott Robertson's How to Draw is a good resource for that sort of thing, and people have generally enjoyed Marshall Vandruff's Perspective Lectures as well.