It’s anecdotal, I took a stake in an ad agency last year and some of the FB campaigns aren’t that much more sophisticated than some of the campaigns a client of mine ran in 2012/2013 (for that client, I was leading the dev team, product and data science team). There are some segments that has evolved, though maybe the larger client was ahead of its time - the ads aren’t actually that much more “creative”.
I do agree that certain campaigns can reach a “fatigue” stage, which means that there’s a need to cycle through. Though, due to the transaction tracking ability, there are some “ever green” concepts that can be pulled out from time to time to test out its efficacy.
And of course, there are caveats around the types of products sold and when the concept is recycled, it’s not a full on re-use of everything being the same, there’s new graphical photoshoot, model swap out and maybe different phrasings.
That said, there are more channels now which kind of makes the different creative approaches that are more relevant to those channels - ie. Quora, TikTok, Snap, Pinterest, Amazon, Twitter, Apple, LinkedIn, In-App, podcasts, AdWords, Newsletter, Substack, Discord - which all have their own approaches that work and may or may not cross with other channels, I am surprised how evergreen once something works though. And yes, there are some concepts which are periodical and never seem to work as well again (podcasting, I’m looking at you, lol).