As I mentioned before, the timing charts indicate the number of drawings that go between the keys and where they go. By this I mean, the timing charts can indicate an even rate of drawings, a slow-out of a key pose, a slow-in to a key pose, or a cushion either into or out of a key. Timing charts must be followed exactly. If you do something to change them, the action will look wrong. Remember when I said, “Timing Is Everything”!
Here are some examples of the basic types of timing charts you can have.
You can slow down your action more by simply adding in more inbetweens. You must place them properly or the action will not move smoothly. For example: if you add in one inbetween to the "thirds" chart between drawings 2 and 3, it will slow the action down in the middle, which you can't do without it looking weird. You would put it either between 1 and 2 or 2 and 3. If you had to add in two inbetweens, they would go between 1 and 2 and 2 and 3, or if you put one between 1 and 2, you could put another between 1 and the new inbetween, which would create a slo-in, or you could put it at the other end to create a slo-out.
Remember, each drawing is shot on two's so it's worth 1/12th of a second.
In the above examples, the numbers are 1, 2, 3, 4, etc. This commonly means that you're shooting the drawings on "one's". If the numbers were just odd: 1, 3, 5, 7, etc. it would mean the drawings are shot on two's. It all depends on how the animator works. Either way is fine, just so long as the exposure sheets are filled out clearly.
Follow the charts or something really bad will happen. I don’t know what it is, but I’ve heard terrible stories of inbetweeners who didn’t follow the timing charts and they were never heard of again. You have been warned!