Packet writing is totally different than direct data burning. Packet writing formats similar to a hard drive I believe,it has headers and probably CRC or some form of error correction for verification, so the drive can time itself to write into the packets (clusters whatever). So that the burning process can be stopped short of having to close a session for every file. All this is so the CD knows how to talk to all the data on itself.
I don't know how to turn it off in INcd from being locked. Direct CD simply had a setting to disable the warning screen that first comes up (or comes up everytime if you leave it on), which basically issues a software eject from reading a hardware request after user approval.