Well I don't know if it's a variation of catmull of not, but the result is quite close ...

And for adding details in zbrush, you have to subdivide your model in, soon ot later.

The only alternative is to do this subdivision with the meshing tool, and don't subivide you model in zbrush anymore. But then, you'll never play with more than 1 ou 2.000.000 of polys, where Zbrush is made to handle 10-15 millions, even 50 millions if you use the HD subdivision technology.

I know exactly what z is made for, I'm using it quite a lot in production.
One the main goal when working with zbrush is to create a displacement map from you're scuplting, and re-apply it in you favorite render software ... So you keep your models light, until the rendering ... where you're again use a catmull/or other sub-d variant, and where bad topology like the example above will get you in trouble.