because program size is equated both pre-RUN and post-RUN.
Once you run the program, the variable space is reserved for whatever you decide to call the variable... rather than having an integer value repeated a hundred times.
All thats left is a single, 1 byte reference to the integer. I could see how this might increase speed of the program as well. Write a simple test program and try it out.
Will definitely keep this in mind for any future programming projects I may attempt. Been far too busy recently to work on anything, but would love to get back to it soon.