To ensure a consistent texture across a large area when plastering, you should work in sections and consistently apply the plaster. This means using the same technique and tools for each section to ensure a uniform finish.  Additionally, it is important to maintain a consistent thickness and moisture level throughout the entire area, which can be achieved by properly mixing the plaster and keeping it moist while it sets. Finally, taking breaks and allowing the plaster to dry between sections can help to avoid any inconsistencies in the texture of the finished surface.