my 2 cents.. April will mark 27 years that I've had number 11 and the most I've ever adjusted the truss rod is 1/4 turn in either direction (add or take away relief). And if I recall correctly, those couple times that I had to do that involved trips from super dry NM to crazy humid Nashville and once when I sent the bass to NY for a freshen up at Fodera..Of, course...to a point. However, if you go beyond that point than you need to flip the rod.
I own 11 Foderas presently...10 of them have the truss rod in the "typical" position (i.e. nut at the bottom of the slot) and can be adjusted perfectly throughout the year without removing the truss rod. One of them has needed to have the truss rod flipped twice per year (spring and fall). Then within each of those 6 month periods all adjustments can be made with the rod in that position...
However, the one that needs to have its rod flipped was only built in 2009, so it will likely settle in to one rod position or the other eventually...either way it is actually my favorite Fodera so the extra 4 minutes of work a year is well worth it! LOL...

