It's all about knowing exactly when to book

Another bullshit idea propagated by blog writers that doesn't reflect reality. Tickets are generally best to purchase about 6 weeks prior to the flight date, but this is hardcore generalization, because each individual seat on a flight is dynamically changing in price at all times. No one can predict the actual price of a single seat in a single fare class and how many will be available. That said though, you can make predictions on if a price will increase or decrease or if the price is higher or lower than "expected". But thats not what those sites do (there are some services out there that do this, but they are different)

you're paying for people who know the market to keep an eye out

These people actually don't know the market really, as I said above and in my original comment, generally what they do is just pick out seemingly random flights where a certain fare category is low, and then show like a ton of them, so you think they get good deals, but in reality they are just warping your ideas

Scott's flights doesn't actually know the market, their business platform is essentially selling you a subscription service that gives you the illusion that you save money on a trip you didn't want to take anyways. It's a solid business model, albeit somewhat weird ethically.

I know more about this than I'm even saying, I'm keeping it classy.... but yeah don't give these people your money.