Inscrivez-vous ou connectez-vous pour rejoindre votre communauté professionnelle.
In general it is healthy to change from time to time. The ideal frequency depends on your personal circumstances, character, industry, role, career stage, and so on.
There are no particular criteria to follow. If you think it's better to say, then stay: if you think it's better to change, then change. It's usually a matter of judgement.