Sometimes, all you really need is one word of encouragement for them to latch onto and to motivate the children/individuals towards success.
I'm mildly dyscalculic, and I can't tell you how true that statement is.
Math classes were so frustrating for me that I was often tempted to just walk out.
To give you an example of what things look like from my end:
The teacher writes a problem on the board, explains step by step what's going on, and I understand perfectly.
She does several others, and I can understand her logic and how to do things very well.
However, if I go to write out a math problem, and try to solve it the same way she did, I make a mistake somewhere along the way. My 7's become 2's, my 3's become 8's, my 4's become 9's- or I just swap numbers around, like 678 becomes 786 somewhere along the line, and I won't realize until I'm done with the problem and have the wrong answer.
What's strange, though, is that I can teach other people how to do the same kind of math problems. People used to come to me for help, because I understood the process perfectly well and could talk them through it- but couldn't go through it without messing up the numbers on my own.
The few times I had teachers who took an interest in me, I was able to progress much more quickly than when I struggled around on my own. Can't imagine what it's like to have someone dedicated to you to work with all the time...
Curiously, I have hardly ever had issues with swapping letters around like that. I actually pick up foreign languages with little/no problem, and can only remember having written letters backwards/wrong a handful of times in my life. I imagine this is something everyone does at some point.
I honestly can't say what the efficacy of a program like this would be, though. The idea of exercising taking away my tendency to change numbers around seems.. far fetched, at best.