"Diversify across 20-30 stocks" is advice I hear constantly, but nobody actually explains how to land on your number.
Every time this comes up someone says "concentrate" and someone else says "20 to 30 names" and someone else says "if you can't follow them all, hold fewer." I get it, but none of it answers the actual question. I want to know if there's a real framework for deciding how many individual names a retail investor with a full-time job should actually carry alongside an index core, not just receive wisdom or "whatever feels right." Has anyone arrived at a real number through reasoning or did everyone get there by accumulating names one by one and then trying to justify it?