When 1:8 sets go on sale

How often they go on sale, and how deep the sale? I learned that when 42115 retired, they went on sale for 30% (although I’m not sure how limited the stock is and how many sets available at this price) Essentially I’m new to collecting LEGO and I have got the first 3 1:8 sets and looking go the the SP3 and P1 but wonder if I can expect they go on sale like the Sian for 30% on their last run, or it was a one time thing so I shouldn’t expect the same for SP3/P1? PS I’m from Canada submitted...