Luiz Philippe Moreira created a handy little tool for changing Maya render settings really easily.

Render Settings such as reflection rays, raytracing depth, ray depth limit for lights, caustics and final gathering, although logically found easily, always seem to be scattered all over the place in Maya when you are trying to change render quality.

A demo on how to use Ray Depth Tool to quickly change reflections, refractions, and max depth for raytracing, caustics, final gathering, ray depth limit for lights, and refraction/reflection limit for shaders with an input value

With Maya Ray Depth Tool, you are able to select the rendering feature you wish to alter from a small interface and add a value that will be used for all of them at the same time, making it simple to change global render settings at will.

Check out the Maya Script for Changing Global Ray Depth Values, the Maya Ray Depth tool here.