Shock, it's amazing what you can learn here . I had a Hakko 936 for about 7 years. Never read the manual on it and never knew that I had to calibrate it each time I changed the tip. I recently sold it along with a spare power supply and using my "clone" Hakko calibrator, both were very close to what the dial showed. The wand had a chisel tip, I never used the conical tip that came with it.
I discovered this after I changed tips the calibration was off. This is what it says:
"The soldering iron should be recalibrated after changing the iron, or replacing the heating element or tip."
"The tip temperature will vary according to the shape of the tip. The preferred method of adjustment uses a tip thermometer. A less accurate method involves adjusting the temperature control knob according to the adjustment value for each tip."
The adjustment value for each tip is an offset temp that is listed next to the tip pictures, many of them say zero offset so I assume they are reasonably close.
In the Hakko FX-888D manual they don't list tip offsets at all, but the FX-888D has an adjustment mode for when you do a tip change, or you could make presets instead if you change tips frequently.
The point is these stations are not designed for frequent tip changes, otherwise you would think the element would be encased in metal or the handle. This is why I brought multiple clones so I could run different tips, an overkill but it beats swapping the tip once you have done it a few times.