like playing the same motif, riff, musical idea etc. but in different techniques.
like the same song or so. but instead of doing it finger style, you do it all picked.
or instead of playing a song that usually has alternative picking, you do all down strokes.
achieves two things:
1) practices the myriad of techniques you are practicing
2) teaches you the SOUND of the technique you are practicing, and how each technique differs in sound. since your eplaying the same thing, that is the common variable. the common denimintaor. and thus what is changing is the SOUND (and also the FEEL). so its cool.