I meant two things. One is the second bullet point Comfy mentioned here with:

https://drawabox.com/lesson/1/7/rotation

Though in the example below, both set of edges rotate by the same consistent amount, their vanishing points will actually move at different rates. How quickly they slide along the horizon depends on where in the frame they are - as the left vanishing point moves towards the center, it will slow down, moving less and less for every degree of the box's rotation. Conversely, as the right vanishing point moves further away from the center, and continues off past the right side of the compositional frame, it will slide more and more for every degree of the box's rotation.

The vanishing points move at different rates.

And basically the intuitions explained here:

https://www.youtube.com/watch?v=rkp1xfWJ9n4

Where the convergences toward vanishing points are perpetually in the middle of swapping which ones are going to go to infinity(parallel) and which one is going to be in the center. The state of each set of converging lines is a blend that you'll want to develop a feel for depending on if you want 1pp, 2pp, or 3pp and what camera lens you want to simulate.

Does that entail measuring/copying boxes with different rates of convergence until you had it memorized or is it through a different process?

A part of it is definitely mileage; developing the intuitions for what angle would establish a set of edges that are 90 degrees from another set, and then again for the 3rd set(basically, the Y method).

It might come entirely down to what you are asking. For some people that might be something they need to do before things click. Once it clicks though, it should be a matter of deducing "ok I want to be looking down the barrel of this gun I'm drawing" and having the ability to immediately know you'll want 1pp with dramatic foreshortening. But it doesn't even have to be in those explicit terms for yourself. It could just be gut feeling and memory from observation.

The rates of convergence really come down to how "close up" to the camera you want to object to feel or, at the same time, how "massive." It is a question of scale and proportion. The typical example is standing at the base of a Skyscraper and looking up to see how dramatic the foreshortening gets as the edges go toward the top. You could get the same effect by looking really closely at a lego.

Like with the gun drawing example, I find it helpful to go through a checklist of thoughts like "am I looking down on, or up at, this thing?" "Is it centered, and if so am I looking at a corner or centered directly on a face?" etc And you could understand the direct implications is has on the vp's. The more natural it becomes the less you have to think in terms of convergences and the more you can just do.

I just happened to see this video on camera lenses in my youtube recommendations. It was pretty cool. Worth a watch.