I assume you know they’re an aid in locating access panels, exterior switches, etc. for maintainers, feelers, etc. and are instead asking why the F-4 feature them more than models of other type. So, I’ll talk about why the popular image of them seems include so much stenciling.
Obviously, all aircraft always come with them new, but it seems like the Phantom continued to be restenciled much more rigorously than other aircraft during the ‘70s when, for some reason, F-4s often received complete stenciling after repaints.I am going to venture that this may have been due to a number of reasons:
One or more of the branches flying the F-4 had a dearth of experienced mechanics as many were leaving the service for the private sector or retiring after having joined during WWII, Korea or the start of Vietnam. So, there were a lot of inexperienced mechanics coming thru the pipeline and they wanted the stencils visible for them.
The F-4 might have had a usually high number of access panels, exterior switches, etc. or some might have been close together and could easily be mixed up, especially by inexperienced mechanics.
It could simply have been that whoever was in charge of these decision was a stickler.
In contrast, one AF crew chief said “that most of the stencils were left off the eagles as they were simply not needed and just too time consuming to put back on for minor panels. They only needed them on the most important and most used panels.”
lol,frankly, I wouldn’t want mechanics who needed stencils to do their job working on any aircraft.
This post I’ve found backs up at least part of my theory that it was dependent on branch:
“The F-4s that went through repaint during the fairly brief interval in the early to mid 70s received the stencils. Based on photos from that time that I've seen, the majority of USAF machines never received the white stencils, but there were still a lot that did. They didn't last long either. I joined the Texas ANG in April 1980 and our squadron of F-4Cs had exactly ONE jet with those stencils. By the time I got to George AFB in February 1982 there wasn't a single F-4E or G in the six squadrons assigned to the 35 and 37 TFWs that still had them.” - Scott R Wilson