Also, how does one come upon these kinds of bits of industry lore? Asking for a daytrader friend. Ahem
E.g. you're an IT admin at Big Co overseeing software contracts. You can often get interesting insights by looking at things like how aggressive their sales reps are with end of quarter discounts (how desperate are they to meet numbers that quarter?). Or if you see a company completely dropping the ball within your org, but on CNBC you constantly hear how great the company is by pundits and analysts -- maybe you know something the pundits don't.
Often times the consensus view of a stock trails reality by a few weeks to a month - there's a lot of non-public but also non-confidential information that isn't readily available to analysts, but exposed to employees of customers/vendors/partners/end-users.
TLDR: when stock picking or day trading, pick companies within the niche of the world where you're a SME.
The example that my business school professor gave was that if you’re riding in an elevator with two executives and they talk about how they’re going to miss numbers and trade it’s not insider. If one of them tells you specifically, it is.
That's why I always shout my inside information within earshot of my financial adviser but never actually place any trades myself.