Yes, this is especially true for cut-sheet devices. Conditioning the stock to the environment and having it as flat as possible is critical for production inkjet devices. The cut sheet ream wrappers are moisture barriers and prevent the sheets from curling. Do not open the wrappers until you are ready to run the stock. The gap between the substrate and the inkjet head is very narrow, so if you're not able to keep it flat either due to humidity issues or improper paper handing, there can be feed inconsistencies and head strikes. Enough head strikes and you'll be replacing your heads prematurely.