Any new design or pattern will present new challenges for you as a wood burner. Each working surface has its own texture, density, and color tone that effect the evenness and final look of each burn stroke. By working a small scrap of the same material you can experiment with your pyrography to insure the best burn possible on your larger project.
My practice board tells me my tonal values according to my temp settings. It tells me how large or small a temp change I need to change the color of an area. Most importantly I can experiment and practice an area of shading, a new texture or a special detailing somewhere other then on my project.