You may often run a desktop application by double-clicking the shortcut on your desktop. It’s fine to do so. But when you are working on a script to automate that process, we don’t recommend you do as the manual way. It is better to use Launch Application to launch those applications instead of clicking from the desktop or even finding it through a search.
Launch Application will only cost you one action to do some steps, such as launch a browser in incognito mode and access a specific URL. If you use that manual way to achieve the same result, you may need some actions to be involved, such as Clicking the browser, Clicking the menu icon to Clicking the new incognito window, then Typing the URL and hitting Enter. This flow will cost you five actions to complete. Compare this to using Launch Application to do the same scenario. You don’t need those extra actions. Just one Launch Application action and you are done!