When to Use GD&T

In this Question Line video, Jason answers the following question regarding basic dimensions and geometric tolerances:

I understand the difference between basic dimensions and geometric dimensions, but I am curious how you decide what features should have basic vs geometric dimensions. In the typical case shown of a square block with 4 holes in it, how is it decided to basic dimension the hole locations and geometric dimension the size of the block? Is it based on criticality of the feature, does it have to do with relating back to a datum feature, or something else entirely?

Jason discusses the below drawing referenced in the submitted question:

In this video, Jason explains the difference between locating features using GD&T and doing so with traditional coordinate dimensions. He clarifies that the +/- toleranced dimensions on GD&T drawings, like that above, are size dimensions and are not used for locating features. Therefore, he rewords the above question to answer when and how Geometric Dimensioning and Tolerancing should be used, and walks through a second drawing in explanation.

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