In a set booster, you are guaranteed to open one, just like you are in a draft booster, but thanks to the wildcard slot and the "foil in every pack" slot, you have a chance at opening up to three rares or mythics in a single pack (and technically four, thanks to the new-to-Modern reprint slot)
It's not useless, but it's not useful or reliable enough to bother with
The remaining two cards I left in the bucket of silica gel, checking every few days until I saw a level of curling consistent with the single-sleeved card
These were all reprints in retro frames, including some repeats of cards serialized in other runs
Ok Booster Box (Pokemon Jungle) Details Full Price Guide: Booster Box (Pokemon Jungle) All prices are the current market price
While Chimecho claims the top spot, it's only based on technicality, as the Umbreon Star and Espeon Star are easily the two most valuable POP Series cards you can purchase