Sice starting more intensive training 4 years ago, I've continuously added shadow training at home with great impact/results.
I simply make it a habit to do some, whenever I have a couple of minutes spare time. It helps a lot that I have a big mirror at home, so I get visual feedback.
Over a short period of time (1-2 months) I'll notice that certain elements of a stroke become more fluid / more automatic.
It's also mostly during shadow play at home, that I "discover" the need to make a correction to my stroke.
eg. last week, after I noticed at the club that I execute my FH loop vs topspin with a racket angle that is slightly too open (45 degrees, contacting back of ball).
It was only at home, making use of shadow play, that I noticed (by feeling and visual feedback) that I forced my wrist backward during backswing, which automatically rotates my underarm a little upward, resulting in a slightly more open bat.
In addition, I could groove the correct technique immediately by using shadow play again.
Of course above correction should preferrably be made by a good coach, but coachin on that level is noy available for everyone.