With this type of spline interpolation, a common problem is the spline
overshooting at extremes when there is a large change in value between
them, especially over a small number of frames. This also happens when
the direction control of an extreme is adjusted. The danger is that,
depending on the variable the spline controls (translate, rotate, or scale), the
value will shoot in the wrong direction just before (or just after) the large
change in value. Sometimes this effect works out well when it occurs just
before a large movement, it may appear to be an anticipation. However,
more often than not, it gives an undesirable effect.