So, many pianist train to strengthen their 4th finger. Schumann is reputed to have done this--and end up injuring himself in the process. At the end of the day, the 4th finger does get involved a lot in the right hand, but not so in the left hand. And I have realized in the last little while that my LH 4th finger is almost unacceptably weak. I haven't practiced scales in a long time, and I noticed that I frequently miss notes when my LH 4th finger is involved. So lately I've been playing B major scale to get it back to shape a little.
I'm not worry about 4th finger playing scales--I used to able to do it well, so after some practice I'm sure it'll be back. But playing double 3rds isn't something I've ever been very good at, and the 4th finger prominently figures in that. I don't think I practiced many double 3rd scales--mostly chromatic 3rds for some reason. So that's probably another reason why my 4th finger in both hands aren't as adroit as they can be.
So maybe I should practice some double 3rd scales. To drive this point home, Chopin's 25/6 is an etude I have such trouble with.
If I have trouble in my RH, it goes without saying my LH double 3rds are pretty much hopeless. The good news is that they truly rarely come up, and when they do, it's only usually for a stretch of 3 double thirds, which I can deal with.
The bad news is... I'm learning Stravinsky's own transcription of Petrushka, and in the third movement (Shrovetide), there is the horror of measures upon measure of double thirds, the LH:
|Petrushka, Shrovetide Fair, Measures 43-44|
Lots and lots of practicing will be required to get this up to speed. Both in my right hand and my left hand.
A Note on my Viola practicing:
Not as much progress as I would have liked. But since this is a post about my LH 4th finger, I'll just say that I am also having trouble with playing a full tone apart on the viola, when it's a 2-3 fingering (i.e. 3-4 finger). It's an almost analogous situation on the piano--weak 4th finger. So in a way, it's good that I'm doing these 4th finger exercises in different ways, because it's useful both on the piano and the viola.