" A lot depends on the level of your students. With some groups, the difficulty they have even reading a meter can keep them from being able to reach any understanding of the underlying physics. "
This may be stating the obvious, or perhaps not, but I certainly hope that, if nothing else, my students will leave the laboratory knowing how to read a ruler. And as a consumer of the education of my fellow citzenry, I'd rather they learn that than some more physics concepts.
My main point is that in my opinion the lab is about a more than merely being a vehicle for aiding the understanding of underlying physics and/or concepts. Naturally I hope the lab is doing that as well.
As always, everyone is entitled to my opinion . . .