I'm gonna check that sir, thank you!
Since are the very fist person to use the word "sir,"(your parents raised you well)
in a reply to one of my posts, I proffer the following detailed response in regards speed practice:
["If speed is your goal then you have to understand the basic tactile nature of playing the piano, and then adapt accordingly, in my opinion, and also that of the late Earl Wild.
So, this is what I recommend, and I have the small hand and spindly fingers to back it up:
This concept is an effectuation of combining direct keyboard tactile touch at an extremely slow tempo, and then morphing it into a Rachmaninoff-like speed tempo. My major teacher, the late Robert Weaver, taught the first part of this to all of his students.
First, you sit very quietly at the keyboard, and that includes your breathing and whole body relaxation.
Next, you very slowly (one note at a time) play a five finger scale in each hand, with super soft staccato. This is done by striking the key from its surface (just the way Egon Petri taught Earl Wild!).
(It is important to rest for a few seconds with hands in lap between each playing because you are building positive muscle memory from the ground up.)
Then, you get it where you can do this with both hands, depending on your own individual level of dexterity. So, when you can do this with no forced effort, you can move on to the speed practice.
From this point on, you view every technical section as a scale cluster, broken chord section, or an arpeggiated section. This is played up or down, hands separately or hands together.
You then play a particular section of the piece in question as fast as you can (up or down, in clusters), utilizing your pre-disposed soft, surface quick staccato tactile sense that you gained from the first section of this discourse. Accordingly, you alternate between full arm weight and no arm weight, resting hands in lap between each alternation (remember, you are training your brain).
I use the term Rachmaninoff-like technique because this is what he taught his students."]
In terms of the thumb, just very, very slightly raise your arm to laterally get to the next set of notes (very slightly). Do it first, whole hand, either to four or five, and then do it to the first note thumb of the next section (alternate back and forth).
And, at top speed, I do not recommend using the supple wrist, just a relaxed wrist. I hope this helps.