You never can tell who will be looking at your work so it should always bear your mark in some way. Add your name and extension to the footer of reports. Insert the same into the source code of a program or macro. Have it displayed on the screen whenever the program is run. Artists sign their work.
Signing shows that they are proud of what they created.
IT also shows that they apply a value to the work. Just like we all learned in kindergarten, sharing is a good trait to learn. In some companies, employees hoard data and use it as a weapon. Departments become little fiefdoms at war with one another. In good companies, though, information is shared.