If you frequently need to download parts of repositories, installing a browser extension can save you time by adding a "Download" button directly to the GitHub interface.
Once installed, you can double-click on any folder in a repository or use checkboxes to select multiple items. A download button will appear at the bottom-right of the page to save your selection as a ZIP.
Similar to Download-Directory, DownGit allows you to create a direct download link for any GitHub subdirectory or even individual files.