Possibly having those fixed promo threads for every season (spring, summer, fall, winter) might help organize the promo threads without a thousands scrolling. Though, again that might be difficult execution too. I agree with that limiting the amount of promos/day would be nice.
Out of curiosity, I roughly counted active threads within last 30 days:
* Art thread : 80
* Writing threads: 50
* Review and Feedback : 50
* Promo threads : 170
So fun fact, currently the number of active promo threads is roughly equal to active art, writing and review/feedback threads combined on tapas forum. What a number!