Drawing Guidance
Traditional animation techniques are based on hand drawn individual frames which when compiled make sequences of moving images. Before the advent of computers, animators' drawings would have been passed onto artists to painstakingly trace onto transparent plastic sheets called cels, after which each drawing was carefully painted with individual colours. Budget and time restraints would dictate the detail and complexity of the animation. More detail meant more work for everyone and therefore more cost. Exceptions to this were epic animations such as those typically made by Disney which featured generous helpings of rich detail and life-like movement.
Loosen-up
Over a lifetime an animator will have drawn literally tens of thousands of drawings. Animating can be slow and tedious and so the last thing the animator wants to do is to spend hours on perfect drawings only to find the movement isn't working. Instead of wasting time, a trained animator will produce rough drawings in preparation for a line tes (see 8. Line Test), and although the result may not be perfect the experienced animator will be able to judge the accuracy and quality of the movement from the line test. Learning to work loosely not only makes animating more enjoyable but ultimately saves time.
Think about complexity
Today although computer software packages have taken over the tracing and painting process it's still a consideration to limit the complexity of the animation to suit the available resources. Even on large budget productions the animator will design characters and objects that can be easily replicated again and again by more than one person.
Separate movement from stationary objects
Animators separate moving objects from stationary objects and so limit the actual amount of repetitive drawing required for each frame. This is done by placing different objects on different layers.
Try it for yourself
The sequence below allows you to switch the various layers on and off. Separating the brushing action from the character's face meant that the face was drawn once whereas the hand brush and foam required 3 drawings to complete the movement.
Are animators good at drawing?
There's no getting away from the fact that to be a good animator you ideally need to be good at drawing especially if you're interested in the traditional hand drawn style of animation. Animators need to be able to draw quickly and accurately. Such skills can be developed over time but the ability must be there in the first place.