One excellent excuse for testing for capacitance that I do is sorting caps for the range capacitors on a function, pulse or signal generator. They are sorted according to the significant digits of the value for each decade. You install caps that have the same significant digits regardless of their actual value. That way, the single frequency-calibration adjustment will be good for all ranges and not just the one range that's used for the adjustment. If you're using an analog dial (or better yet, restoring an older generator), the overall accuracy of the instrument is improved by a full magnitude that way. Yes, you can use a counter to measure the output frequency in actual use, but for many applications (alignment of an antique radio comes to mind), you don't need counter accuracy but would be content with better than off-the-design-shelf accuracy for an older instrument.