It depends. On most orders, the client expects a finished product upon delivery. You should never use the “Deliver Now”-button if your work isn’t complete in your eyes.
The best practice is to deliver the completed work, and then review any requests for revision as needed unless otherwise agreed upon before the order starts.
On larger projects, I find that buyers sometimes will ask for me to complete a portion of the work, send it, and they will give it a go-ahead or let me know if they want something done differently. I’m usually fine with that, as long as the order is already started. I never work for free.
This can be a good way to make sure that you and the buyer are on the same page, and allow them to give you some direction if needed.
But in most cases the buyer will place the order, I will complete it, deliver it, and then they can ask for revisions. If you’re in doubt when you’re working on a project, you can always ask for feedback from the buyer along the way.
A nice way of dealing with large and time-consuming projects is to use the Milestone function when you create the order. This allows you to set milestones, and you’ll be delivering on those, and then the buyer can choose to proceed to the next milestone.