Here’s a great way of strengthening your ability to quickly play the chords in any key. Pick a key for the day that you’ll work on. Let’s say it’s C major. Play all of the chords that are in the harmony of C major. First, use as many open chords as possible. Next, play through the harmony using bar chords only. Try using as many different voicings for each chord within the harmony. Play one chord after the next as quickly as possible, maybe even use a metronome to help you gauge your progress. Try this with any harmony that you think you may not be so strong with. Have fun with it!