Code location

Where do you put your code in flash ? Do you put it all on the main timeline ? Do you put in on the objects ? Where is the best place and why ? I followed a few tutorials where all of the code was on a layer in the main timeline (for arrangement). I kind of liked that but as I advanced in flash I started having problems with specifying the hole path for every movie clip (sometimes 7,8 embeded movieclips). I find it much more easier to just put the code on the movie clip itself. What is your method and why ? Are there any advantages/disadvantages for every method ?