I can see the issue now. The only thing I can think is if you say the utility allows 3 attempts then pauses for 1 minute, this setting must either be built in or gets taken from the framework settings, even though this says it only relates to full disk.
Maybe you could review your framework settings to see if there are additional settings that will help. i couldn't see any that specifically lock a file though so it would only be strengthening it a bit more, which you may not wish to do.
Sorry I couldn't be more help.