You can work out how well the thread dial works in various pitches fairly easily; chuck up some scrap material & turn it so it's turning true; then set a very light cut (0.001-0.002", 0.02-.004mm), get everything turning, then engage the half nuts as the thread dial indication "1" touches the marker (you don't have to be nanometer accurate, the nut will engage only when the dial is in the right place, unless you're way off).
Turn a short spiral, then back the tool out & disengage the half nut. back the carriage away from the work, feed the tool back in to the same depth as before, wait for the thread dial "1" to come around again, and repeat. You should find the tool following the same spiral. If it does, try again, but engage on the "2", "3" and "4" of the thread dial. Again, it should always follow the same spiral; or maybe you'll end up with 2 spirals (one for odds, one for evens). If you get the 1 spiral, try again on the 1/2 marks.
Now turn the spirals away so you've got clean stock again, change from metric to imperial (or vice versa), and repeat the exercise. If you get random spirals each time, then you can't use the thread dial in whatever range your lathe is set to. It's also worth trying on a few thread pitches, to make sure it behaves the same way no matter what.
I ought to try that myself tbh, I've never actually done it on my lathe...