Say I had invested in Amazon 15 years ago and I was constantly trimming because it was overweight. Would that have been better for my portfolio overall or would I regret it?
Of course the answer to that is dependent on what you would have bought with the proceeds from the Amazon sale. So unless you keep a very exact record you will never know.
Perhaps the biggest pro of keeping something for a long time is that dividends may grow until it becomes a cash cow , 20% +returns nearly guaranteed based on original price thus giving you some piece of mind in bear markets. And keeping something means only one decision , thus only one chance to make a big mistake, whereas buying series of replacements gives way more opportunity to really screw up.
I rank failing to hang on to some stocks like AMZN and NFLX as my biggest mistake in over 40 years as an active investor.