CNS-PER-CNS BOC?
I guess if these are already planned within 10 mins of the limit any delays in PER would mean a cancellation of the service, or a diversion en route should unforeseen circumstances mean busting these limits.
Knowing what PER is like from personal experience, I'd hazard a guess and say a delay of more than 10 mins would happen quite a lot. I guess these diversions/cancellations due to exceeding stick limits happen very often then. If not, why not?
Are guys knowingly breaking the rules? If so I'm sure the company appreciates your efforts, but good luck keeping your licence if CASA gets wind of it.
There is one simple bullet proof answer to all of this.
JUST SAY NO!
You have a legal requirement to refuse to fly if you feel fatigued. Use it!
The only reason you're rostered the way you are is that you continue to put up with it. Grow a pair.