Paper Shortage?

This is one photo from the early 19th-century documents collection at Thomas Jefferson's Monticello (recently posted on social media).  The following explanation was offered alongside the picture:

Although it may look odd today, crossed letters—also known as cross-writing or cross-hatching—were not unusual in the early-nineteenth century. Both paper and postage were expensive, and this technique allowed the correspondent to save money by writing in one direction and then turning the letter 90 degrees and writing perpendicularly.

The penmanship of the period always seems to be precise and straight.  Now, with cross-hatching, the writing is as artistic as basket weaving.  What an interesting sidebar in history.