AS3 code -> frame of *.as file?

Hello everyone!

I would like to hear from experienced AS3 users: are there any kind of rules or ‘good behavior’ on where to place a code for files.

Should one use *.as files instead of frames to place code?

I mean, yes *.as file is pretty easy to track and modify. But there are a lot of stuff that could be done using frames.

What do you think?