I got permission from Drite.
In this type of calculation, before assuming that the characters did not move at all or only moved 1 pixel, their height above the ground in both panels must be determined using pixel lines. If their height above the ground is different in the two panels, that means they moved, and the snail’s speed cannot be used.
For example, in
this calculation it is assumed that the knife did not move at all in the air. However, when I checked using pixel lines, I can see that the knife’s height above the ground is different in the two panels.