How do you manage discount deals on your saas?

Saas businesses run discount deals periodically. They add banners or pop-ups to their websites to show this deal.

I'd imagine it takes some significant effort across both the sales and development departments to prepare for and launch these discount campaigns. If they have to do this for multiple holidays every year, the cost of manpower adds up.

How do you manage discounts on your saas? Any tools you use to save man hours?