I don't think anywill will argue the point that parsley boxes do look wonderful. And like most I can attest that my average appearance scores went up once I started doing them. However if I could give two pieces of advice for those just converting.....
1. Depending on how you place your entry on the bed of parsley, the middle may not even be visible (this is the case with my ribs, brisket and pork) So I don't kill myself making the whole box look perfect for those entries, I just focus on the edges.
2. Boxes are usually the last thing I do prior to getting a little sleep. So, I'm already tired and in a hurry to be finished with doing them. Have an extra head of parsley for touchups in the morning. You may find yourself wondering what you were thinking when you thought the box was good enough the night before.