I would draw a distinction here.
If the goal is strictly to ensure respect for individual rights, then the personality-based approach can be useful. There may occasionally be criteria for a sufficient number of people, but in theory, anywhere you might be in Canada, you can use the language of your choice. In terms of individual rights, the approach has some merit.
However, as for the development of the language and its survival through generations, the personality-based approach does not really yield effective results, because the dominant language will systematically take precedence.
It is therefore important to determine whether the objective is only individual rights, or whether it is a broader objective to enhance the vitality of the language and its development. Consideration should probably be given to both. Traditionally, however, the federal act places a little too much of an emphasis on language rights. The approach has not been very effective from the socio-demographic standpoint in the 54 years since the adoption of the initial Official Languages Act.
As for the application of Bill 101 to federally-regulated undertakings, the Quebec language act, the Charter of the French Language, goes beyond Bill C‑32 in protecting the right to work in French. It is not just an act, but also a fundamental right. The Office québécois de la langue française possesses the expertise required to interact with private undertakings and coach them through the francization process. The federal Commissioner of Official Languages, is much more specialized in dealing with public institutions. In the few instances in which the Commissioner attempted to have the act enforced in private undertakings like Air Canada, these efforts were only moderately successful.