While I'm sure 275 for 12 minutes will allow PC to cure "strong enough" to handle most shooting needs and pass the smash test, I'd prefer to follow manuf's instructions to cure the powder. They've spent a LOTS of money developing the powder, and figuring how best to cure the powder to max strength.
I use Smoke's powder, and I'm sure he uses the manuf's cure instructions, so I tend to follow Smoke's advice for curing PC.