If you've done a lot of work in Excel, you know that you can select multiple rows or columns, use the Copy command, and then right click and select Insert Copied Cells. But you can only do this once per copy, and there's a faster way.
Select however many rows (or columns) that you want to insert - it doesn't matter if they're empty, but they must include the location where you want to perform the insert. Now click anywhere within this range of selected cells, right click and select Insert. That's it. Any existing content will be moved down (or right) to make room for the number of rows (or columns) you had selected.
You can repeat this as many times as you need as long as your rows (or columns) remain selected.