Will the Sims 4 Business & Hobbies EP go on sale during spring sale?

No one doesn't really have definitive information for that here. You'll just have to wait and see.

Usually new packs being on sale I don't usually see for a good few months based on the usual patterns. If it does it probably will only be about 20-25% off. Probably won't be til summer time until you see anything half off for the pack. (Or usually when there will be another major pack after that)

Let's put it this way: Lovestruck came out last summer, and in the sale last month, it was only 30% off. You're probably looking at another year, maybe even two, before this new pack is 50% off.

It all depends on sales. If simmers are not buying the new EP as predicated then it will go on sale sooner before later.

Probably not because the ep is way too new and will only go on sale after the next ep releases. Initially the pack will go 25% off and after a few more months, 38%. After a whole year the pack will finally go 50% off and will be able to add it to a create your own bundle. As someone who will only buy packs on sale, but I will pay for B&H full price along with GTW when the sale period starts this month, I am constantly checking when packs go on sale but I can't be bothered to wait a whole year just to get this pack at a reasonable price.

Yeah, it definitely varies, but I can't remember the last time I saw one go on sale for 50% off in less than a year. It seems like that's sort of the threshold, and then it could be even longer if sales are still strong.