I checked my HF 1/2" drive with a set of scales and it was accurate to within 3-4 pounds throughout its range.
I never carry one while traveling. The only thing that for the most part is lug nuts and a tire store can recheck your work.
Everyone should know the approximate weight/leverage, etc of their own lugs IMO. Get them close and you are fine in most cases. Recheck when you get back to civilization. My van is 100 ft. lbs. so 80 plus is good for me.
BTW some like the beam type wrench but it is sometimes really hard to put the proper amount of torque on them and still see the scale. I use a small magnet and place on the scale and set it next to the correct number and when the needle hits the magnet I'm close enough.
">Magnet in place to stop at 100 ft. lbs.
">Simulated stop at 100 ft.lbs.