Advice on managing iMovie Library

Question

I'm using iMovie 11 and need some advice on what exactly the iMovie Library is, and how to best manage it.
If I understand correctly, the iMovie Library is a collection, sorted by date, of video footage imported into iMovie. This footage can be used to create Projects, Trailers, etc. Is that accurate?
As for managing the iMovie Library, my question is this: once I create a Project or Trailer with the Library footage, and said Project is complete and shared or exported someplace (such as iMovie Theater or iTunes), is there any reason to keep the iMovie Library Footage?
I ask because I honestly must have about 60 different assets in the iMovie Library, most of which is video footage from old tape-based cameras. I'm curious what most other people do with that footage once a Project is complete. Is it common to keep, in case you want to create a new Project? Do people normally delete it?
Thanks in advance.

Answer 1

pmpknetr21
You raise an interesting point.  From my perspective, and I have a lot of both old tape & newer chip based video footage. I tend to keep it either in my MAC iMovie library (latest events) or in an additional iMovie library on an external drive (older footage-especially old Tape based).   That way I have retained an electronic version of all my video footage which I may or may not need in the future, (without the need to re-input).  Retention somewhere is certainly a requirement if you wish to modify a project in the future.
I also use Time machine for all my back-ups and this backs up both iMovie libraries, so I maintain safe historical data. 
Retention is really a personal matter, plus cost of storage, but given disk storage is relatively inexpensive I retain mine.  I have approx 8 years worth.
Hope this helps
Colroy