I always do it with the left. I know it sounds weird but its just what im used to

I only use my right shift.

How did you know that?

I am used to the use of left shift for the all the letters I know. I don't think there is any difference as long as I get the correct letter on the document.

I write with my left hand and I use the right shift the majority of the time. I think often people tend to use the opposite hand to shift rather than the hand that they write with.

I believe it would be much better to use both shifts and deciding which one to use should rely on where the letter you are capitalizing for example, would sit. If it's on the right side of the keyboard, then use the left shift and vice versa. I believe this would help with speed and performance.

As for the space bar I always use my left, but I wouldn't think that any side matters in this case because your thumbs are strictly reserved for the space bar and they would not or at least should not be hitting any other keys.

Wow this is an interesting question. I barely even notice which fingers do the typing anymore lol. But let me stop and see.

A (right shift)
B (right)
C (right)
D (right
E (right)
F (right)
G (right)
H (left)
I (left)
J (left)
K (left)
L (left)
M (left)
N (left)
O (left)
P (left)
Q (right)
R (right)...

ok we get the idea. It looks like it depends on whichever hand is reaching for the letter, the other hand reaches for shift. Causes less stress for fingers and is also faster. I would probably recommend this method to others.