How accurate does a torque wrench have to be?

If you want to be accurate, use a beam wrench....

So a beam type torque wrench would be good to ensure that the torque settings are accurate when building my motor? It's on a stand so I can easily see the dial.what type do people usually do to assemble a motor?

I guess I am probably just being overly cautious because I really don't want to have to pull this motor apart again...