FCRA 605A(a) states that initial fraud alerts remain in the file of a consumer "for a period of not less than 90 days, beginning on the date or each such request, unless the consumer or such representative requests that such fraud alert be removed before the end of such period, and the agency has received appropriate proof of the identity of th requestor'
It is thus calendar and not business, days. It does not affix a date when it is removed, it states a minimum period.
I would presume it is done by automated software at each CRA, so should be fairly consistent, but no specifc date is requred aftr expiration of the 90 days.
They may not run that software every day, so I would not rely on a precise date.