Good point on the details. I am thinking that also on a lot of lesser bikes (that had protruding nuts/bolts used for securing derailer claw mounts and fixed axle stops), that additional axle protrusion was added to accommodate these features without the bolts contacting the freewheel.
Even many bike's rear hubs set up for 5 speed freewheels (and with 120/121mm spacing) had room for standard 6-speed freewheels if these bolts were shortened to the point of being flush.
Campagnolo 5-speed hubs did not feature these excesses of axle protrusion, the better to preserve axle longevity, but cheaper French hubs very often did.
And especially when using modern chains, the outer face of the smallest cog can be as close as 3mm to the inside dropout face in some instances! Very little excess axle protrusion needed.