Chord changes - most efficient way to practice them?

Martin Zimny had an interesting lesson on something that wasn't about chord changes, but he does discuss some approaches to efficient learning of chord shapes.  This was at least 2 years ago, and I *think* the lesson was on Villa Lobos Etude 3, but I might be making that up.   

Also Lukasz Kuropaczewski has a new lesson on practice approaches.  you'll get some good things from that one. 

Lots of teachers could talk at length about ways to practice chord changes.   there are so many principles to approach it well.   

The new course on practice by Łukasz Kuropaczewski is probably an excellent approach to practice progressively chord changes.

https://app.tonebase.co/guitar/courses/player/lukasz-kuropaczewski-practice-principles?moduleSlug=lukasz-kuropaczewski-practice-principles

Having in my youth used the guitar only to accompany songs, when I approached classical guitar a couple of years ago I tended to change chords even when the strings were not played all at once. Then I realized that I can move my fingers one at a time as the individual strings are played. I write this because I, too, try to play that magnificent piece that is Cardoso's Milonga and in doing so I adjust as I have written.

Although I'm not sure if there's a lesson exclusively on chord changes, there are lessons on techniques and on pieces that touch on chord changes. I can think of one lesson that talks about shifts- Gael Solal' lesson on Carlevaro techniques.

I'm no expert but here's a few things I learnt.

1. Fingering choices are very important and can have an influence on the ease of shifting from one chord to another.

2. Use of guide fingers or ghost fingers whenever possible instead of jumping directly by lifting all fingers.

3. Sequential planting of LH fingers, instead of planting them all at once, especially on arpeggios.

Hope that helps and good luck.

Perhaps this will help you:
First practice each chord separately- find a good fingering for the chord, play it 2 or 3 times, then remove your hand from the fingerboard, let the arm fall and relax for a few seconds
Repeat this 5 to 7 times
When you have mastered the first chord do the same with the next chord
Remember to relax your arm and fingers for a few seconds
Next play the first chord, let your arm fall, relax and then play the second chord
Repeat this 5 to 7 times
Next fetch your metronome
Count four beats
Play each chord ONLY on the first beat, not earlier, not later
The sound between is not important, concentrate on playing on the first beat
If you have mastered this you may count 3, 2 or 1 beats, playing only on the first beat

Voilá
Good luck