How accurate does a torque wrench have to be?

Lol that post makes a bit more sense now.

I went out and did a few more tests on my big and little wrenches. I think my weight was a bit off last time, I varied the weight by a few pounds each test to see a bit of a range (I'll maybe do some more extremes too) I did three total tests, the average with the big wrench was 3.44% and the little one was 3.37%.

The big one was bought about 2 years ago and not used often, and the little one was calibrated in 99 but not used often and stored right as far as I know, is the need to calibrate based on use or time? Because from those numbers both seem pretty accurate, also have to take into account the margin of error with my testing.