The workshop manuals from my older vehicles (not Holdens) would specify details about the TTY bolts (which have all been head bolts). As part of the specification, there would be a maximum length clearly defined for TTY bolts, which when exceeded would require the bolt to be replaced, as well as progressive torque settings (and angle in some cases).
Now I havent looked into the Holden VF workshop manual in detail but i think it simply states if the bolt is to be replaced with no mention as to maximum usefull length. I can't believe Holden would make them so flimsy to be single use.
Guess it's all part of the modern day mindset and the dumbing down the popluace where manuals are not needed for the things we buy as service is something that is not done by us owners but farmed out to 'professionals'. Oh well.
But testing bolts is reletively simple. So if anyone who has bought new caliper bolts cares to do a such a test, then simply measure the length of the new bolt using a caliper gauge, then measure the length of the old bolt. Install the old bolt using Holdens recommended torque setting and process, then remove and repeat the measurement and reinstall. If they are TTY, they will get just that little bit longer after each use. And after a number of reuse cycles they will snap if they are TTY. It may take 5 or more cycles before they let go.
It shouldn't take more than 10 minutes to do this and will answer the question once and for all...
But please check if and how the snapped bolt can be removed before taking it to the extream as i wont be held responsible for a stuck brocken bolt (though i suspect it should be loose and come out easily).