All over the place, there's a bunch of little good deals.
Mostly I ignored these for years - and I think it's smart to not go chasing little things at the expense of bigger things. If you've got some creative or business skills, there's almost certainly some better use of your time than cutting coupons.
Starting about a year ago, though, I became a much more serious student of marketing. I'd paid plenty of attention to marketing in the past, but 'round about a year ago, I started systematically paying attention to it.
Part of that was just interacting more with the world - including actually checking out the numbers on all sorts of offers, things I'd have normally ignored.
Some of them are pretty bad. A loyalty card where you buy-10-get-1-free isn't a very good deal. It's basically just a 10% discount, but worse because you might not get the discount, could forget or lose the card, means you've got to carry more junk in your wallet or bag, and so on. It can be an okay thing, maybe, if it doesn't change or inconvenience your spending habits - but that's why they create the things, so you do go to the inconvenience of going to their place more often and spending more there.
Sometimes though, deals are fantastic. A number of companies that know that the lifetime value of a customer is big for them will offer quite significant loss leaders to get you in there, and that's real. Sometimes you'll see a credit card that'll give you a $750 bonus for signing up if you've got great credit. (That's valuing their points at about one cent each, which is straightforward if 10,000 points = $100 statement credit and they're offering 75,000 for signing up)
Also, it's often possible to get an expensive high margin item for free regularly. I tend to work in cafes a lot and order a lot of coffee, so my annual coffee cost is kind of insane. But that number is drilled down a lot when there's something like this -
Pacific Coffee in Hong Kong has a member's card where you put like 200 HKD on it to start ($25 USD) on it to start, and then there's some promo each month. When I was in Hong Kong last, it was buy one drink, get one free. Okay cool, I usually get 2+ coffees and sometimes 4 when I work a lot of hours in a cafe, so that shaved a lot of money off my coffee bill. Starbucks has offered similar things in the past the in the USA.
The majority of little offers are junk and they're definitely not worth chasing around if you've got other skills. But if you're generally curious about retention and loyalty programs and customer acquisition in business anyways, it's both fascinating and about 1 time out of 10 you ask, what they're offering could be good.
Money doesn't care where it came from - if your annual coffee bill goes from $1200 to $600 for a few minutes of buying a Pacific Coffee card, then that's $600 more in your wallet at the end of the year for a few minutes of work. Not worth chasing after regularly, but useful if you're standing in line anyways to look at the brochures.