Here's a great way to make multiple viewports the same size and spaced evenly on a page in your layout tab.

Open a blank Layout tab and set your printing device and paper size.  Type in VPORTS at the command line and hit Enter.  The Viewports dialogue box is now before you with a list of standard viewport configurations to choose from.  Select four equal as a test, set the Viewport Spacing value to .25" and pick the OK button. A final Enter to accept the Fit option at the command line and Puff!  Four equal viewports with exactly .25" spacing now appears on you page.  Much easier than the old MVSETUP command of days gone by.