In my (excessive) exploration of the gradcafe forums, I have heard lots of people (perhaps predominantly physical science people) talk about expenses paid recruitment weekends. My question is are these common in our field (esp. Pure Mathematics?) There is some discussion that some of these serve as a way to recruit almost certain admits and make one final check that said admits are not crackpots, and others serve as another round of competition via formal interviews.

I am applying to

Texas Austin, Utah, UIC, UPenn, UCSD, and Arizona with an interest in arithmetic geometry.

Does anyone have any idea whether (broadly) this is common practice in math, and (specifically) whether this is common practice at any of these schools?

Thanks in advance