Mystic publishes a flyer which shows all of the USA stamps issued during 2018. This is usually the way I purchase my USA stamps along with the 2018 supplement. I plan to quit after 2019 when my last album is filled.
The pre-packaged USPS commemorative year sets sometimes don't have all the commemoratives for that year. So the face value of in the packet cannot always be determined by referencing a catalog. One of several reasons I stopped buying the year sets 3 decades ago. For example, the 1976 set only has one representative stamp from the 50 state flags issue. But I also recall single commemorative stamps also being left out of one or more year sets. Also, I'm not sure if they consistently include commemorative airmails or not.