We do alot of shadowboxing at our gym, every trainingsession starts with it. We also shadowbox with each other (like sparring, but without touching eachother and with enough distance) Not only good for technique, but also a steady warming up when you do it really relaxed purely on techniques. At the end of the training we also often do shadowboxing, and then it's more 'serious' which means: faster, more power in the airpunches, faster moving etc.

A benefit for starting every training with it, is that also beginners do it (with guidence) , so there's no embarresemend for anyone to do shadowboxing. And it's fun. Just pretend you're up against any boxer you like (no-one knows, it's all in you're head ) and pretend how you're going to knock them down