The shape doesn't matter for the scaling as long as it is a 3-dimensional object that is scaled in all directions.

And I think for the actual value you get, scaling by volume would actually be more accurate.

The original took 144 years to build, and this model is anywhere between 153 to 278 times smaller. If one were to scale by volume, the build time would take at most 22 minutes, and at least 3.

I think scaling linearly works better here

Well that’s because you’re building alone and there were multiple people at once doing the real thing, and it’s a different construction method.

That only determines a constant factor though, the scaling of build time for a given method should roughly follow volume.

Would you say that building a Lego version that’s twice as high takes double the time?