Did your CoFounder "earn" their equity? (I will not promote)

Usually when startups form they give equal shares to CoFounders (not always). Curious for folks here who are maybe a couple of years or more past that point - would you say your CoFounder "earned it" from the work and contribution they made thereafter? I think some of these insights might be helpful to an awful lot of people on here that are going through that decision process right now.