No, I don't know how many times they have to do it. Clearly, there are a certain number of programs that require it. Of course, every time someone finds a new job and has a new employer, they have to provide their social insurance number.
Also, for all federal government programs that offer benefits, the individual must provide their social insurance number. Everything hinges on where the individual might be in their life cycle. Some have the same job for many years and rarely have to give out their social insurance number, whereas others have to do it frequently.