What do you do in order to build a musical image for yourself?
Memorization, yes, practical theoretical/harmony comprehension, yes, quality physical motions, yes. But there's something more which makes the music alive.
Singing is a huge component for me in this. Being able to sing every or very many parts of the music (from memory) while playing another part, even if it's not counterpoint. Being able to hear everything in stereo and each of the individual parts but also how it all fits and functions together.
In the learning process, quicker decisions and more confidence enacting them, less time rehearsing it as merely a blob of sound (because you're scared of being wrong if you make an actual decision). If you're scared of making an actual decision that's "wrong" and you're scared of rehearsing it the wrong way for some amount of time, remember it's actually still wrong to rehearse it without decisions and as only a blob of sound. At least if you're making decisions but have to change, you're using that mental muscle and growing it when you make changes.