My DS s teacher has him work on the same sheet at the same time but has acknowledged it just isn't going to happen quickly as he just can't do it. So she has him do as much as he can and that's it - but she does insist that he get them right, so he has to correct them like everyone else. Basically she exempted him from doing it timed. I think it's legitimate - after all the point is to make it rote not the speed for speed sake. My only complaint is that he never finishes the sheet. I wonder if he needs to even at his own pace - but she doesn't make him do it. Also, I have pointed out to her that he can do them in his head but the writing screws it up, the same with spelling. So I think sometimes she also tests him orally. Our goal here was for him to not feel too bad about not being able to do it. I am not worried he isn't getting the math. If you are worried about the math then definitely have him work on it without the timing, either though an app or flash cards or something. But otherwise, the timed stuff is about translating rote facts quickly, not just about the memorization. And my DS just can't do that.
DeHe