Yes! The direct checkout option lets you skip the cart and display the fast checkout straight away.
This is an excellent idea if you need a quick way for customers to buy one product at a time. This is how it works when you enable direct checkout:
The customer adds a product to their cart.
The popup checkout opens immediately, either on the right hand side of the page or as a centered popup (depending on your settings).
The customer enters their details and pays directly in the fast checkout.