So I wonder how senior a person gets to decide these tiny questions? A clerk in the purchasing department, or the director of marketing?
From the last two companies I have worked at, it was the CEO in concert with the DFO who made such decisions. I would hate to think that marketing would ever have a say in such things...they already try to influence a flight ops department too much!
Anyways, going back to my previous companies. They had a number of sequential registrations reserved from the regulator and would decide on an annual basis whether to continue the reservations (funnily, it wasn't cheap). Sometimes they would decide they wouldn't need as many and let the reservation lapse.
Sometimes though the regulator simply runs out of registrations within a "series" and the airline takes whatever is next in sequence to be issued. Although from a spotting view it may seem silly, from an airline point of view it's just a tail number so there is not a second thought given.