Interactive Zoom Ratio
When using a very long animation layer, it may be discouraging having to use the sliders continually to only view a section of the timeline.
Fortunately it is possible to modify the timeline scale thanks to the button ( ) at the right right in the layer options.
Click and hold the button of the timeline to modify its display (stretch or increase the icons from the current image depending on the left or right movement of the mouse or trackball).
With a right click on this button, the Auto Fit popup menu may be used to adjust the size of the icons in the timeline in order to view the entire project, the clip, the current layer, the current image, some exposures, the current selection, some keyframes or the sound.
You can also use [Alt] + RMB + movement on the right or on the left, respectively to zoom or unzoom in the timeline.