With experience, string players become accustomed to the required shape and position of the left hand.
For example, fourth position on the cello (used in the example below) has the player's thumb resting in the "saddle" of the neck root.
Similarly, higher positions on the violin make use of the instrument's "shoulder" (treble-side edge of the top's upper bout) as a touch reference.
[6] In reference to classical guitar, "Fernando Sor recommends that one should 'be sparing of the operations called barring and shifting'.
As a result, trombonists often spend time studying a part to determine how to approach a particular phrase.