New to PC, does GOG not give you a sale end date ? :( pretty rubbish if not

There are no countdowns or dates given on individual product pages, but every sale promo page (ones like this one) -- which can be found via the front page and/or via news posts (which are also found on the front page, at the bottom) -- has a countdown, which should also appear on the relevant promo "card" in the "Now on sale" section of the front page; bigger sale events like this one also tend to have some sort of countdown or end date (for the event as a whole) visible right on the front page (currently, it's right at the top). Also, those news posts I mentioned (for example, this one) generally mention the end date (and usually time), as well.

Thanks for the in depth reply, much appreciated :)