If employees say they "forgot" or they are in too much of a hurry to make entries in the signout book, one idea of mine is to put a signout clipboard on every shelf, for the items on that shelf. Multiple lists makes more work for the person who complies all the records, but it might be less work overall than resolving inventory shortages. If you are clever, you can figure a way to mount the clipboard so it is vertical in the middle of the shelf and the employee has to move the clipboard in order to get to the stock on the shelf. Whoa! They can't say any longer they forgot about the signout list, which was in their face, which they held in their hand.
Maybe you can think of refinements on this idea for your situation, like cover a bank of shelves with a clear plastic curtain and to pull the curtain back you have to move the clipboard.