I'm not sure there is one definitive answer to this question, as there are so many different individual circumstances to be taken into account. Some experts advise holding about 10 percent of your net worth in silver/gold as portfolio insurance against depreciating fiat currencies and possible hyperinflation,etc. I think this is a good starting point. For example if you added up the value of all your assets including stocks/bonds, IRA, 401k, savings account, etc and let's say the total was 200,000, then you would put 10 percent or 20,000 into precious metals. If you had to take some money out of savings or other investments to purchase the PM, it would be well worth it. Then I think diversifying storage rather than keeping it all in one location is a wise idea. Never store in a bank deposit box because you won't be able to access it if the bank goes on one of those notorious bank 'holidays'.
Great comment my friend, appreciate it.