WD,
What's the descrimination setting your using on your machine? That the meaning of disc. if you knock out some of the lower range of targets you might miss the odd keeper but dig way less junk.
It's a matter of preference really since most my sites are pounded to death I just knock out iron. This year I'll probably even dig the iron signals.
Another factor of descriminating the lower range is you risk loosing some depth and there's a nulling out factor which comes into play. Let's say you knock out pulltabs there's a good chance you pass over gold rings also which quite often fall in the range.
Are you confused yet because I can give you some more confusing info if you want....

