Why do some ATO tests pass only for certain Workset Sizes?

[ikalash]

@jrobbin : I noticed after Dan's change to the default workset size in Albany that a couple of ATO test solutions (2Matl and RegHeaviside_3D) are workset size dependent -- the solutions are a few decimal points off with a workset size != 50 (50 was the old default workset size), causing the tests to fail. We should understand why this is happening to make sure there is no bug underlying these differences. Could you please have a look when you have the chance?