Do you intend to play repertoire which demands such things? If not what's the point? If one piece you want to play had it, is that really efficient use of time just for one piece?
Okay, so I have a habit of asking questions that depend a great deal on the individual pianist and so can hardly be answered with any precision, but it's a habit that's hard to shake, so I'm here to ask another.I watched a Josh Wright video where he plays a scale at up to 220 bpm, with four notes per click. This got me wondering what some reasonable BPM goals would be for the various scale types, for an advanced pianist like me. I'm by no means a virtuoso, and I've got a lot of deficiencies in technique to correct (hence my wanting to set some scale goals to work towards). I can play most major and minor scales hands together at about 140 bpm, or hands separately around 150. My current goal for this year is to get up to 180.But in trying to set goals for, e.g., scales in double thirds or octaves, I found myself unsure of what goal I should set. What speed do you think most professional pianists could play double thirds scales at? What about scales in octaves? I suppose it also depends on the scale, since some are more awkward than others.Also, I'm not accustomed to practicing double notes scales consistently. While I have not tested my limit for scales in thirds, I'm sure it does not exceed 85-90 bpm.
A few years ago I would have said that BPM targets for scales were completely a waste of time and that focusing on getting the right motions and the right sound would more or less automatically improve speed (and that is what my teacher at the time would have said, too). Then I watched the same Josh Wright videos and it changed my mind. After working up to the same range you are at with standard scales I find that the metronome is very helpful. Keeping a record of scale speeds really showed the impact of poor sleep or mild illness. More importantly, by forcing myself to work at progressively faster targets I identified all sorts of subtle problems in motion that could be experimented with and optimized in scales and it helped me in general with all sorts of faster passages that were not themselves straightforward scales hands together up and down over four octaves. Exactly because the notes are automatic it let me focus on all sorts of small physical sensations and details that I would have missed otherwise, and because there is a benchmark with the metronome, it helped me see what worked and what did not. I'm sure you could go too far with this if your tendency was to turn everything into an athletic exercise, but I think if you have an ordinary love of music, you'll probably steer clear of that anyway.As for the double thirds and octaves, I have not started timing any of those. My guess is that the thirds would be a lot slower, at least at first. I just recently started making targets for arpeggios, and that too seems to help me figure out what motions are more or less efficient than others.
I think there is a general value in developing such skills. The insights into technique you get from developing the ability to play certain technical feats can be applied to all repertoire you play and help you improve your playing across the board. But I also agree there are better uses of your time perhaps, if you are just gonna slog through it for the sake of it.