"A Lot Can Go Wrong"

First position, shifting to third position. I've been doing that since, what--sixth grade? Seventh grade? I use a first-to-third-on-each-finger-in-turn shifting exercise as a warmup before every practice session. Granted, that exercise is so automatic for me now that I sometimes am focusing on something else--my bow hold, say--while doing it, but I'm shifting in tune.

And double stops. In the Bach, I had to do double stop fingering in a couple of passages even though there weren't actual double stops. Since I've started working on the Haydn, Ms. L. has had me doing double stop exercises of various kinds to prep me for actual double stops there. 

So when I saw this, I wasn't worried. 

However, it seems as though I am spending a disproportionate amount of practice time and lesson time on this, especially the first two sets. (I'm playing the third set on two and four, by the way, not one and three.) That shift from B+G to D+B is killing me. I only get it right about 40% of the time. My usual error is playing both 3rd position notes sharp, but the B is the one most likely to be wrong.

I have practiced it as follows:

• Super slow-mo, fingering and playing both notes 
• Pausing before each shift, fingering and playing both notes
• Fingering both notes, but playing the top note only
• Fingering both notes, but playing the bottom note only

For what it's worth, when the same pattern comes up again a few measures later, I get that one right about 60-70% of the time. It's as though the concept of short-term memory applies to muscle memory as well. It's not really a perfect analogy, but just as I might babble a phone number under my breath for a few seconds until I can dash across the room to a pen and paper and write it down before it vaporizes, my fingers seem to remember what they are supposed to be doing between the first instance and second instance of this pattern. Or else they treat the first instance of the pattern as a rehearsal or "first draft" and make the necessary correction on the second one.

I asked Ms. L. a couple of weeks ago, "Why is this so difficult?" and she shrugged and said, "It's shifting. It's double stops. A lot can go wrong." I guess it just needs more time and (careful) practice.