In short….. Spontaneity and unpredictability are the properties of life. And where there is life, these properties must be present in one way or another.
As an animator, your job is to create an illusion of life, so you’ll have to spend most of your time creating that ultimate flavor of life by bringing spontaneity and unpredictability in your work (do not take unpredictability as something negative. It’s sometimes good for your animation and adds life to it.). So you’ll spend a lot of your time creating texture and contrast in your timing (holds, offsets/delays), poses (silhouettes, line of action, flow lines), spacing, net displacement (vertical and horizontal), and character behavior/emotions, etc. All this will help you to bring that flavor of life and make your animation stand out. Otherwise, everything will tend to look mechanical and robotic, and there will be no spontaneity of life.
For example, consider this simple hopping ball-character (with a tail doing secondary). If you scrub through the animation you’ll soon come to see that I’ve played quite a bit with its timing, spacing, and its displacements. Get a metronome (you may use THIS one!)and play it at 92 BPM and watch this animation. What do you see? Yes, the hops are timed at around 92 BPM but the poses are not hitting on even timing. This adds more contrast so that the motion doesn’t look rehearsed or mechanical. I may also break some rules at this stage and just start playing with my shot. This is very important and helps you add life and believability to your animation, and everything appears to be more organic rather than being stiff and mechanical.
Contrast in timing is very important to natural-looking motion. Even jazz composers break up the rhythms they have created to make their music more interesting (I was a percussionist/drummer in my junior high and high school orchestra so I know this very well!). You need to do the same to your animation and adjust the timing of the motion to have greater impact. The timing of your poses should have a natural feel, a rhythm, texture, and flow, much like great music. The beats and the rests in the music between the verse and the chorus to hold interest, and so should your animation.
Look at the above image. The second hop is a lot quicker than the first one. Notice, the last hop is going higher than the rest. This makes it look more interesting and adds life.
So, PLAY with your timing and move your frames around until the timing feels natural. This goes for any kind of animation (CG, 2d, or stop-motion). Nail your poses and then finesse the timing. The finesse step is the most difficult part of animation and also the most important!
Hope this helps some of you. Best………….