I'm not proficient at SDKs, but have incorporated them in the last year and do 2-3 off of every wall in practice. But something I have noticed- they feel much better in practice than they do in a race.
If you want to use them effectively in a race, you have to practice them at race pace. Otherwise, you'll just be shakin your groove thang down there.
I intend to do more 50s (in short course) where the swim is close to race pace, but the walls are at 50 free race pace. These drills will have gobs of rest, as the intent is to concentrate on technique and feel at speed.
I'm sure there are other ways to improve your SDKs in a race and not just in practice, but this is something I intend to work on.