This will cause dimpling. Boards of the same width or alternate sizes offer a good appearance. Make sure that you butt the wood tight because there will be shrinkage as the wood dries out. If you install the deck using straight planking, you can allow some overhang and trim for a more finished look by adding fascia. Pressure treated wood is not protected from sun and water.
Wood swells when it becomes wet, shrinks when it dries.
These stresses can cause cracking, splitting, and grain raising. Most products can be applied within 90 days of finishing your deck. Make sure the sealer contains protection for ultra violet light.