I think pitch practicing is like trying to get a tan while wearing a wet suit. What will help you in achieving a better “hit” ratio is by having a solid and somewhat predictable play technique. And by play techniques, I have tried MANY. I even thought of calling myself the multiple personnality disorder play technique Thereminist. I have been playing for 2 ½ years now and only recently I have yet changed my technique to what I think will be probably the one that I will stick with. The thing is, if you want constant results with your playing, you have to somewhat control the environment that you will be playing in. I mostly play in my music room and that place is pretty predictable, minus the cat or the dog walking around me. 2 factors that you will always have most control over is YOU: How you play and how you play. Yes, how you play as in what technique you are using and the other one is standing up or sitting down while you play. As for play techniques, some offer more flexibility in the expression department while being less “precise” on constantly hitting pitches (and I say this loosely as you’ll always have to nano-adjust the pitch of each note as Peter Pringle said): others have given me more predictable results while being less flexible in the expression department.
One thing I have noticed over the last few months is that standing up to play is a big disadvantage to the thereminist. It is somewhat impossible to stay still when you play, so by parking my derriere on a Drummer Throne, I have truly improved the precision of my playing by at least 75% (my non-scientific conclusion). I have also quite small hands and found that trying to play with a knuckle extension technique wasn’t conducive to the results I was trying to achieve. All this time, I really didn’t like how Carolina Eyck played as it felt so robotic like ~ but I’ll be DAMNED! By changing to her technique, it has allowed me to aim for increased precision and have a better time and fun too in my practices. I can actually say that I love it now... I feel that I can start progressing rather than trying to keep on finding a play technique that would suit me. I have found it, so now I need to work on getting more and more at ease.
Playing the theremin musically will take YEARS of devotion to the instrument. You’ll have many nights of tears, cussing like a sailor and hours of dealing with the devil in trying to sell your soul for being a theremin God (or Godess).