Would you sell a stock for 5% yield and buy something else?

I would recommend Your individual predefined.

However, I do not favor new single stock investments anymore in my case.

When You buy only global, and particularly U.S., passive indexing stock ETFs you are as to stock investing well-diversified. You just buy & hold (ideally 'forever', whatever that means),

no worrying over market noise, crashes, valuations, incredible technical analysis, etc.

You could just relax, check the portfolio rarely, even abstain from often advised 'rebalancing', almost no work, just (probably) excellent longterm returns

Assume that you do not have any shares in the stock, would you buy it at the current price.

If yes, carry on and hold. If no, reduce your size or sell them off.

It depends on your investment objective, as well as the future prospect of the stock itself. If it has reached your profit margin level and you have better things to do with the money, then sell it.

Here is everything about me and what I do best.

Congrats on finding a gem. That said you have to ask yourself if you are able to find another company which can give you higher share price appreciation or dividend yield.

If yes, you may consider to sell, if no you might want to continue holding