Not saying that this exact thing could happen if you don't check headspace - bolt lodged in your shoulder - but something similar could DEFINITELY happen if your headspace isn't even verified - and it's off, and very tight or very loose...
If you don't check it, you won't know until you pull the trigger the first time, too... I'm just sayin'.
In reference to the 308 ARs, there IS no set standard, no pattern to go by, and definitely no TDP to follow in producing the parts for them. Hell, there are three MAJOR different platforms/patterns in them, and by now, possibly thousands of manufacturers of parts, components, barrels, etc.
You can probably build any AR-15 variant you want, not check headspace, and you'll just be fine. Please check the headspace on your 308 AR build, though. Not for us. For you.