The pressure treated wood you get has a grade jargey3000 and I have given you a link above that shows you the grades and what they are for.the PT wood we get around here is pine, I think, pretty soft...and the "pressure-treatment" is pretty thin. With the constant pounding it gets from our weather - 7 months of mostly rain & wind, & 5 months of mostly snow & rain & wind, NOTHING stands up very long..it gets ugly pretty quick.
not a pretty picture...
Of course if you don't ask your supplier what grade the wood you are buying is, then you will not know if it is a good choice for your intended application or not.
Again, not all wood including pressure treated wood is created EQUAL. When you write, 'the PT wood we get around here', it sure sounds like you are thinking like many people do that it's all the 'same' and you have no choices to make.