The ideal business is one that earns very high returns on capital and that keeps using lots of capital at those high returns. That becomes a compounding machine.
If you know how to value businesses, it's crazy to own 50 stocks or 40 stocks or 30 stocks, probably because there aren't that many wonderful businesses understandable to a single human being in all likelihood. To forego buying more of some super-wonderful business and instead put your money into #30 or #35 on your list of attractiveness just strikes Charlie and me as madness.
If you expect to continue to purchase stocks throughout your life, you should welcome price declines as a way to add stocks more cheaply to your portfolio.
If you own a wonderful business...the best thing to do is keep it. All you're going to do is trade your wonderful business for a whole bunch of cash, which isn't as good as the business, and you got the problem of investing in other businesses, and you probably paid a tax in between. So my advice to anybody who owns a wonderful business is keep it.
Long ago, Ben Graham taught me that "Price is what you pay; value is what you get." Whether we're talking about socks or stocks, I like buying quality merchandise when it is marked down.