Estimating vanishing points without actually finding them

Halfway through a big perspective box exercise and I keep catching myself doing something I'm not sure is helping. When I need to figure out where lines converge, my instinct is to ghost the line way out past the page to locate an actual vanishing point, then work backward from there.

But I think the whole point of the exercise is to train your eye to feel the convergence angle without physically tracing it out. Like, you're supposed to look at the existing edges and estimate where the next line should go based on how steeply things are already converging. Not find the VP, just sense it.

I'm torn because the ghosting method gives me more accurate boxes right now, but it might be a crutch that keeps me from developing that internal sense of depth. When I did gesture studies, I had a similar moment where measuring every proportion kept me accurate but slow, and loosening up was the thing that actually built real skill.

For anyone who's ground through perspective construction exercises like this, did you let yourself ghost out to the vanishing points or did you force yourself to estimate purely from convergence angles? Did one approach build your spatial intuition faster than the other?