If the detector was nulled out 90% of the time, you probably were missing good targets. If you're looking for coins, reduce the discrimination and listen to 2-tone ferrous. Dig the high tones and ignore the low tones. If it still nulls out a lot, minimize the rejection levels. A smaller than stock coil would also be a good idea.
As to what program I would suggest you ran....... I suggest you build your own. The programs that come "stock" on the E-TRAC are fine for learning the detector's functionality. But they are just a starting point, as far as I am concerned. Everything in any of the programs can be tweaked to fit the individual. Learn what each feature is and what effect it has on the performance of the detector. Then build programs that account for your style of hunting, the type of sites you visit, the amount (and type) of trash in the area, the number of tones you are capable of processing, whether you want to hear the audible from the ferrous properties vs the conductive properties, the length of tone, etc etc etc. Once you understand the functionality of the E-TRAC, and the flexibility it provides, you can set it to operate well at nearly any site imaginable. And once you get what you perceive to be the right combination of settings, save it as a program on your machine knowing (again) that anything can be tweaked at a later date. JMHO HH Randy