The RNG pool is used for creating: the master key (for encrypting the data in the volume), temporary secondary key (for generating a pseudorandom stream to initially overwrite a volume's empty space), salt (for passphrase hashing, using pbkdf2), and (optionally) a keyfile.
That is all limited to the process of setting up a volume, and so the RNG pool is not used for typical operations on a volume after that volume is created.
http://www.truecrypt.org/docs/random-number-generator
The RNG pool is used for creating: the master key (for encrypting the data in the volume), temporary secondary key (for generating a pseudorandom stream to initially overwrite a volume's empty space), salt (for passphrase hashing, using pbkdf2), and (optionally) a keyfile.
That is all limited to the process of setting up a volume, and so the RNG pool is not used for typical operations on a volume after that volume is created.