Question about quarters

To my memory severance floors have been opened for 12 years. And in S2E5 we learn there have been 882 quarters. Irving was alive for 12 quarters and worked at Lumon for about 3 years. So this implies there are 4 quarters a year. But if that’s true how were there 882 quarters. Were quarters a thing before severance and they continued into severance or is there something weird with the timeline?