Take the example of older days when computer graphics didn't exist like Tom and jerry in 50s or hand drawn animation in Paper Flipbook in modern times .
see https://img-9gag-fun.9cache.com/photo/aV3M8NK_460sv.mp4 for example
How are animators able to draw the same image in same proportions at same spot over several frames almost flawlessly?
clearly without any aid its not possible to draw the same object on each frame at same place and with correct size and color as the last frame.
how do they accomplish this?