No. The techniques are not rare. The situations where such techniques would help are relatively rare because front-end precision is usually less than ADC resolution. A typical 10-bit ADC is perfectly good for 0.5% accuracy. Actual signals being measured are usually less accurate. In such situation, there's nothing to gain from oversampling. But people do it anyway.Not sure what your point is. Incidentally, I wouldn't call the technique of increasing ADC resolution by oversampling and decimation rare by any stretch.