Losing even a few minutes of your work can be frustrating. Highland 2 has a way to prevent this from happening.
Go to Highland > Preferences… in the menu bar (or press ⌘ Command + ,) and select the Backup tab.

There you’ll find checkboxes to back up your writing either as .highland files alone, or .highland *and* plain text.
You can also select what folder you want to save your backups to, and how often you want Highland to automatically create backup copies.
If you ever have an issue where it looks like you’ve lost your work, make sure your first stop is back at this menu to click on the Go to Backup Folder button. You can check there to see if any writing you’ve lost from your main file was saved as a backup copy.