Glad you enjoyed my gifset!
I don’t recall reading this before about John’s part. Let’s see if it’s accurate.
STUDY IN PINK, parted on the right:

BLIND BANKER, parted on the right:

GREAT GAME, parted on the right:

SCANDAL, parted on the right

HOUNDS, parted on the right:

REICHENBACH FALL, parted on the right:

EMPTY HEARSE, parted on the left:

SIGN OF THREE, parted on the left:

LAST VOW, parted on the left:

So what can we deduce from this? Grief makes you change the way you part your hair? Love makes you change the way you part your hair? John was so desperate for excitement after Sherlock’s death that he changed the way he parted his hair? Personally, I think the change was just to emphasize the passage of time. But good observation!