Have you downloaded the emulator and had a practice before you get it?
Brilliant machines and was very impressed with mine. I had 2 programs set into the machine and used either of those or the factory presets. I found that covered all I wanted to.
I would start off with the factory settings for a few outings until you get the hang of the display and the sounds. They do take a little bit of learning.
Besides all the settings you can program in, you can also "colour in" the display with the bits you want to discriminate out. Just like using the rubber function in "Paint". I just made the left and upper left corner of the screen black, this discriminates out most iron.
I definitely didn't dig every signal, if I did that I would spend an awful long time digging up rubbish. Depends how thorough you want to be. There has got to be some compromise between digging every single piece of carp and missing the very occasional goody along the way.
I always figured that if I somehow did manage to miss a goody, it was there for next time.
Having said that, I hardly ever dug up rubbish without thinking it was most likely rubbish first.
Damned good machines, good luck with it.
ps. they are stupid heavy and unbalanced in my opinion, and I sold mine. Shame, as they really are impressive performers once you learn them.