I consider myself an intellegent person, I hold down a good job and have good qualifications (I also score 142 in a Mensa IQ test - if you believe in that sort of stuff). However, I never ever mastered my times tables and I went to school in the 70s - we were dismissed each afternoon by being asked random tables questions, if you got it right you got to go - I was generally the last person to leave primary school every day :o(. I was as it turned out later, a whizz at maths, but useless at Arithmetic. I can't say that it has particularly held me back, but I do find it frustrating at times.
My eldest son who I think is about the same age as your Sher is the same as me - I have had him crying in frustration, as I'd like him to be able to have the multiplication answers at the front of his head rather than struggling with them. There really is no substitute other than to just keep trying to learn them by rote. He is very clever otherwise, but I really feel that this holds him back. Part of me wants to tell him that actually you can't be good at everything and when you are grown up you get to use a calculator so it doesn't really matter and that would be good for him to accept that he is not perfect. On the other hand I think it would do his self esteem and confidence good just to overcome this.
I don't think the school is going to help him any more so I think we need to take your method and just get him to learn them regardless of the tears!!!
Well done to No 1 son though - hope he spends his bribe wisely!