Transposing a passage into neighbouring keys is a very useful practice device for the left hand. Rather than practing the same difficult passage over and over, we can create some useful variety by transposing it into neighbouring keys. This serves to reinforce our technical mastery while at the same time it stops us from getting bored with endless identical repetitions.
While this idea works especially well for passages in thumb position it can also be used in the Neck and Intermediate Regions, but only in passages that do not require any open strings. We might think initially that it is not possible to transpose passages which use natural harmonics, but in fact this is not entirely true. Those natural harmonic notes will just need to be stopped in the transposed versions, but this doesn’t do us any harm at all. On the contrary in fact: when we have to stop all the notes, this reinforces our positional sense even more than when we use the harmonics.