Étude

The string repertoire has a canon of them: Wohlfahrt and Kreutzer for violin, Dotzauer and Popper for cello, Simandl for bass. Each étude typically targets one thing, string crossings, a particular shift, a bowing style, and repeats it enough that the pattern becomes automatic.

The distinction from an exercise is that an étude is written to be played musically. Practising one with no attention to phrasing or tone extracts perhaps half its value, since one of the skills being trained is applying technique inside real music.