New member on previous subject (dog houses)

Am writing this as a new subject simply because the subject was brought up a few months ago and never seemed to get a complete answer. Tender dog houses many times just seemed to be a RR preference but the obvious answer is that there was just not enough room in some locomotive cabs for a third seat, with the Pennsylvania and some N&W power being the most obvious. Others, such as the Missouri Pacific appeared to just want to get the head brakeman out of the cab. The opposite example might be the B&O, that went out of their way to extend some cabs and keep him in the cab. The KCS mounted dog houses slightly off to one side on Vanderbilt tenders and at least one southeastern RR (maybe the Clinchfield ??) partioned off a space inside the left-front corner of the tender, so had tenders with one small window on the fireman's side. Am short on time right now but would like to follow up later with possibly more thoughts on this subject.