This can be tricky stuff because you are working one rotation against another. (yogauonline.com)
You see, actually judging the physics of No Time To Explain, the force required, the angles and the distances, is bloody tricky stuff. (wolfsgamingblog.com)
Really tricky stuff, like the virtual TIO that tripped up Holland, goes to the 18 - member rules committee for interpretation and revision. (si.com)