I'm reading "The Jazz Piano Book" by Mark Levine, and he often says things like "learn this new voicing in every key". What's an efficient way to do this? I've tried "practicing around the cycle of 5ths" but this doesn't seem to create the association for me between the letters and shapes. Practicing chords in tunes seems to work better but is slow and piecemeal and doesn't cover all keys. (And I'm not good enough to transpose tunes quickly ... because I don't know many voicing, a bit of a circular problem!)
There are 2 things : associating the voicing with a symbol and being able to play it.
For the second part, playing the voicing along the circle of 4th / circle of 5th / chromatically / randomly is a good way of getting the voicing under your fingers in the various white / black key shapes.
For the first part, I suggest two things: 1. say the voicing name while practicing the shape and 2. play the voicing in a chord progression: find a chord progression in which the chord appears (or can be substituted) and play it making concious use of the voicing you are learning. Repeat in 12 keys. :-)
Singing the root notes of the chords is also a great idea (especially when playing rootless voicings)