AE ENHANCERS

I can't tell you how awesome this is for projects that bring in a ton of layers from FCP via Automatic Duck. Just amazing

Alex

After Effects CC (12.1) adds an option in the Precompose dialog box for this, to trim the precomposition duration to the duration of selected layers.

See this page for details:
http://adobe.ly/AE_CC_12dot1_details

For comfort I've modified the script "Precompose and trim to layer length.jsx" to place it as a dockable palette. I found this script really useful and thanks to all developers.
hope this updated script might save you even more time.

Can download from the link below
file name: Precompose and trim to layer length Dockable.jsx

https://drive.google.com/open?id=0ByXUcJJ4U9Utd2NvREFncGJTeW8