Are torque wrenches worth it?

Clean decent quality bolts etc don't vary by anything like that amount in operation, and the smaller the bolt, the less the variation. Modern wrenches are very accurate indeed. So between the two...
Many bolts have a light coating of lubricant to deter oxidisation. I suppose that some will clean anything that might be on the bolt (and nut). Some might put grease on the thread before. Others might put some anti-seizure compound on the thread. I have an old bike so some bits are a bit rusty, with the original plating / coating gone but the whole part is still very serviceable. Other parts have the original zinc coating coming off in tiny bits. Not all my bolts and nuts are new or made of the same material, or have the same finishing. I might some day have the whole lot to be all consistent, but I don't think I'll ever get there.