Keep experimenting with notch if you like - it is fun to experiment with settings because you never know what you will come up with. Unfortunately, with notch, you also will never know what you are actually missing, too, if you inadvertently notch it out. The more I have thought about what you are doing, the more I think about how difficult what you are trying to do really is. Let me illustrate. Notch works best when both your desired target and "trash" have very little target ID variability. For example, notching out zinc pennies at the beach is pretty straight forward because you can easily determine the TID range where the clean and mildly corroded zincolns will fall and just notch that out. If you are looking for high conductors, then no problem you can even tweak it to be able to snag wheats if you want while leaving the zincolns behind. Highly corroded zincs will have lower TIDs and you can just ignore them. Similarly, if you are detecting in an area such as a patch of beach where you run into a bunch of pull tabs, chances are they are coming from the same 12-pack or case of beer and all of those particular pull tabs will likely have similar TIDs and those can also be "situationally" notched out with a narrow notch until you get past that patch and you have a much smaller chance of missing that rare gold item that would just happen to fall in your notch range. But what you are trying to do is find the right set of notches for most pull tabs or pieces of can slaw which is daunting because even aluminum pull tabs have a rather wide range of TIDs when you consider all the varieties and it gets even more variable when you consider bent and broken tabs. Now combine that with the fact that gold jewelry TIDs are very highly variable depending on the size, shape, and composition (purity) of the gold. You are trying to notch a moving target (TID wise) "aluminum" without inadvertently notching out another moving target "gold" and your chances of notching out the gold just skyrocket unless you have one very narrow notch like I described in the "patch of tabs" scenario above, and then in that case, how many tabs are you really notching out if the tabs can be of any shape and type.
Regarding silencer, -1 is recommended because higher numbers risk the chance of one-way masking of non-ferrous targets in the presence of iron. In thick iron, higher reactivities are your friend because they enable more separation between targets. That is why XP saw fit to turn silencer off by default for reactivities 2.5 and greater. Silencer will certainly quiet your detector down in thick iron situations, but there are no free lunches. It is a filter, and like notch, or even discrimination, use of any filter to knock down the audio or filter the TID of undesirable targets risks also filtering out desirable targets. The only filter I regularly use is discrimination. I use it not because I do not want to hear iron (because I DO use iron volume, so I can hear the iron even if it is discriminated out), I use it because it helps to prevent ferrous TID down averaging of non-ferrous targets. More experienced detectorists tend like to hear it all or hear most of what the coil is detecting and let their brains and more importantly their shovels be the discriminator.
If you want to increase your chances of getting gold, the best method of doing so is finding the site that has the highest probability of gold drops - that typically is at the beach, in the water, where jewelry slips off of folks fingers and wrists as they first enter the water with the second best being the towel line where people lose their bling by intentionally taking it off before they go into the water. Since detectorists know this you either have get there before the other detectorists do or because gold sinks rather quickly out of detector range, hit eroded parts of the beach to find those really old drops.
The other place is sites where people gather (parks, concert venues, picnic areas, campsites, and old home sites). The problem with that is the drops/losses are less frequent than at the beach (i.e., less replenishment) and typically these are also the places hit hard by detectorists, not surprisingly, so your best bet of finding the gold is to hit those trashy areas that may be masking it. That seems to be your situation and finding the gold there is not going to be easy as you have found.
Good luck on finding the elusive gold.
I should add that your perseverance should eventually pay off so keep plugging away.
