For well over a century this organization has been proclaiming that mankind is living in the last days of this system of things and that Christ has taken position on his heavenly throne 1874 , 1914 since these dates mankind is supposed be living in the last days of this old system of things as written in the bible.
The question that could be presented were these set doctrines really devised to enhance the proliferation of the WTS own printed works, but not necessarily backed by bible scripture or in fact going against bible scripture pertaining to false prophesying ?
I think that Russel may have been sincere in his belief in these end time prophecies. JWs weren't the first group to become fascinated by dates and Russel was influenced by other adventist groups. Of course Russel was also a businessman and invested his life savings into religious publishing. Being bold and going against the accepted theology seemed to be his selling point. I think as time has gone by the leaders have become less sincere although they still hold onto some dates like 607 and 1914. They know that these were false and mistakes but JWs have built their theology around them so they hold onto them. 1925 and 1975 were probably used to motivate growth in the org, the leaders knowing full well that there was nothing special about those dates.