The Alexander Technique is meant to be applied, and this is the focus/goal of the work. But...dependent on your stage of learning (and life circumstances) you can speed up your development by better balancing your Alexander Technique 'deep practice' with you AT 'application'. You can think of this like the difference between practicing your instrument (deep practice) for the show, and actually performing the show (application).
Now you could just practice in your basement and never play any shows, but you'd never develop your ability to handle and enjoy interacting with other people and environments. On the other hand, you could just play a whole bunch of shows and never practice but, especially in the early stages of learning, you simply might not give yourself enough clarity with the work to improve on the mistakes you keep making. Thus, you ingrain bad habits and slow your progress.
The truth is the answer to what your balance should be is something largely based on and determined by your goals. The key is really to not completely ignore one for too long.
My balance this morning is at about 5% deep practice and 95% application. These days when I'm really 'on' it's probably more around 10-15% deep practice and 85-90% in application; for instance I shift the balance more this way so that when I teach i'm definitely 'on' for my students (teaching keeps me sharp!).
When I've gone through big learning jumps, especially in the beginning, it was likely closer to 40-50% deep practice and 40-50% application; and usually I took it too far.
So what's your balance between deep practice and application?