The last time I saw an Origin wide sale was Sept 2016 (I don't check regularly though). They had a 50% off sale to promote the new Origin UI/look. I got Dragon Valley, Roaring Heights, and Barnacle Bay. I thought 50% off was pretty good, and with the gold versions of DV and RH the simpoints essentially came at a nice discount. I bought the related venues for both worlds off the Daily Deal and spent the remaining points on other sets. I thought it worked out to be a pretty good deal.
30% off is obviously not as good as 50%, but these site-wide sales on Origin seem fairly rare to me. Actual TS3 packs might go on sale from time to time on Origin, but I've never seen the worlds specifically go on sale. With the current 30% off sale I decided to get The Sims Medieval. I've been checking Origin every now and then for about 4 months and decided 30% was probably the best sale price I am likely to see anytime soon.
All that being said, I haven't yet played a game in DV or RH yet. :( I did play a short challenge in Barnacle Bay, which is a nice enough world and played with virtually no lag (I had NRaas StoryProgression off too in that game). Someday I'll get to DV and RH though.
I would say take advantage of the sale if you have the money. If not, be prepared for a long wait for another site-wide sale on Origin.
