I do not userecommend against exercises that focus so heavily on expanding between 4-5 and 3-5. StretchingStretching between 3-5 and 4-5 is uncomfortable, can be prone to stressing the tendons across the top of the hand, and tends to promote twisting laterally at the wrist, which can also lead to tendon and muscle irritation. Although music sometimes demands 3-5 or 4-5 stretches, an exercise that repeats them frequently I would stay away from.*
In the setting of a piece of music, it is rarely necessary to shift positions using 3-5 or 4-5. Encountering that situation would always prompt me to look to find a better option.
The contraction exercises are less risky, but here, too, there's typically a better fingering option.
Were I to encounter these patterns in a piece the proposed exercise patterns, my most likely fingerings would be:
4-3-2-4 3-2-1-2
or5-4-3-5 4-3-1-3
5-3-4-3 2-3-4-1
or4-2-3-2 1-2-3-1
3-2-3-2 4-3-2-1
4-3-2-1 2-3-4-1
Position shifting aside, there are times when one does need to expand between 3-5 and 4-5. To design exercises, I would create patterns that open the entire hand. This tends to flatten the hand, which naturally expands the space between those fingers while also shortening the difference in distance to the keyboard. (One of the core issues is that 5 is so much shorter than 4 or 3. The difference is mitigated by a flatter hand.)
Here are right-hand exercises I might consider. The same principles could be applied to the left hand and, with some additional creativity, to the kind of hand-shift exercises in the OP.
X: 1
T: 3-5 / 2-5 Expansion Exercise
M: 4/4
K: C
L: 1/8
"1"C"3"G"5"c"2"G "5"d"3"A"1"D"3"A | EBeB fcFc |
X: 1
T: 3-5 / 4-5 Expansion Exercise
M: 4/4
K: C
L: 1/8
CBcA dBAB | B,ABG cAGA |
X: 1
T: 4-5 Expansion Exercise
M: 4/4
K: C
L: 1/8
CBdB Dcec | Edfd Fege |
* Hanon does includes these expansions, but there are two key differences: 1) Hanon allows for the hand to contract after each expansion, and 2) the expansions go from shorter finger to longer finger, which is less stressing than the reverse.