Come to think about it.......... 
During 34 years of making a living, on grown up machines. I never trammed a mill. 
David D
Hmm, dunno what sort of a workshop you were in, but the joints I happened to frequent, required me to spin the head at very odd angles with some jobs, or, if there was a bit of a boo-boo on my behalf -----------------------s-o-o-o-o, do the tram again.
Some jobs even required I tram it before I started, as the tolerance on the drawings were a tad on the tight side.
With a couple of different operators using the same machines, you could never quite trust the way the other fella left the gear.
Most of the mills I had to operate over the years were of the same sloppy design as the Bridgeport, and I soon discovered it was easier to lower the quill and tram that, by raising and lowering the table, do the X axis first, then go for the Y axis, much quicker and believe it or not, a lot easier that trying to spin the quill and tram the table in the normal fashion.
You could get the head absolutely spot on to the table, each time you trammed the quill.
regards greenie