Every not common, binary file will bring huge security
Except that the thief could then either dl every non-common file or run the program on your machine relative to it. I think I would only do this if the file were on a removable drive. But then there's the chance of losing the file.
A passphrase is still the best option, imo.
I don't think he will download my 1k+ photos, and my 2TB external drive full of musics and films
With a 100MB file, it takes 5 seconds to calculate one private key
Use a 700MB movie, start at key number "your birthday+your phone number"/"your credit card number*your age"/"whatever" instead of 0, and nobody will never ever find your private key
