When you create geometry at full size, the resulting drawing is often too large for standard-size drawing sheets and title blocks. Thus, you insert the title block at an enlarged scale and then reduce both title block and drawing geometry when you print.
For example, if the drawing geometry needs to be reduced by a factor of 4 to fit on a drawing sheet, you insert the title block at a scale factor of 4 and enter 1 plotted unit = 4 drawing units in the Plot dialog box. This setting reduces the size of the geometry to 1:4 scale. The title block, at 4 times size, is also reduced to ¼ scale. Since ¼ 4 =1, the title block plots at true size.
If you use preprinted media, you can still use a title block as a guide for entering text and determining the drawing borders. You then delete or freeze the title block before plotting.