I guess all things change with time!
I noticed a post the other day about conductors in a spare motorman's cab and it got me thinking. I also rode the 14th St/ Canarsie Line daily for 3 years between DeKalb and 1st Ave and then for another 4.5 years between DeKalb and 8th. I don't remember a conductor at any place other than the middle door of a mid-train car on the Standards.
This was in the early 50's, and I'll admit that I was more interested in assisting the motorman up front.