Not sure if you’ll agree with this article… Perhaps this piece should be called “To Each Their Own” instead of the very definitive-sounding title? Sounds like an article title and “fund strategy” intended to drive clicks more than anything.
When we buy an opening position in a stock, we size it at 3% of the portfolio. It’s big enough to matter and focus our attention but not so big as to unduly harm the portfolio if we’ve made a mistake. As we learn more about a new company, having lived with it for a while, we’re more comfortable adding to the investment if the price gets lower.