Jack, it depends on the quality of the gun you use and the air pressure you set your regulator to and in some cases, the CFM that is available at the gun (not just at the compressor, hoses lower the CFM).
If you 'know your tools' you can trust an impact gun to be within a range. For example, with my Snap-On 1/2, set to its lowest setting, on tightening, it is just about 50 ft-lbs. So I'll use that for initial bolt/wheel tightening.
If the bolts you are removing are clean and unmolested/rusted, slowly dialing up the setting on the gun or air pressure can get a good gun to just barely loosen and then left to the same setting, can tighten pretty closely. But you have to know your tools.
Mostly, I use a tiny Bosch 1/4" cordless impact gun to run the bolt/nut in then follow up with the appropriate torque wrench if precision is called for or I use my 'inner ninja' for non-critical ones. After spinning wrenches for 40 years, I am pretty accurate by hand. But I do not risk 'by hand' on alloy wheels or cylinder head bolts.
Always be sure threads are cleaned and use anti-seize/loctite/oil/dry as called for.
My general rule is a lost bolt is better than a stripped or broken one.