If I follow the recommendations (or rules) from Mazda shop manuals all cylinder head bolts, connecting rod bolts and main bearing cap bolts must only be used once.
What experience do readers have from perhaps ignoring that rule and re-using bolts?
Any failures resulted?

 

Which Mazda vehicle are you referring to?

On all of the imported US and North America Mazda trucks, B2000, B2200, B2600, and B2600i from the model years 1986 to 1993, I have always reused the factory bolts when rebuilding the engines.......never had a problem either!

 

I have a BT50 from 2008 with the 3 litre, 4 cylinder diesel enginr

 

Then those are more than likely, the Torque-To-Yield bolts, and yes, you should replace them. They are only good to use once.