Timing work for a struggling child

A friend of mine named Cindy told me about timing a child's work to help them succeed;. The child I homeschool took all day and could not get his work done.  I would spend an hour and a half to try to get his English finished.  We were both miserable.  I was not succeeding in teaching him.  Cindy suggested I try timing him and then moving on to the next subject when the time was over.  I gave him 10 minutes to do his English and then I assured him it was enough.  I put the paper back in my book to be worked on the next day.  At first, it took a week to do a day's work.  As I learned to accept what he could do, he grew more confident and could do more.  He was so concerned he was not doing the paper correctly he could not work. Now he can do a paper in two days and is close to finishing one day's lesson in one day.