What must masons rely on when choosing desired course heights?

The reliance on scales when determining desired course heights is important because scales provide accurate measurements and help ensure that every course is laid correctly and consistently. In masonry, precise height measurements are crucial to maintaining structural integrity and ensuring that the finished work meets design specifications. By using scales, masons can verify dimensions against the project’s specifications, ensuring alignment and balance throughout the construction.

Measurement tools such as scales also allow masons to make adjustments and check for level as they build, which is essential for achieving a polished final product. While other aspects like blueprints, experience, and course length play important roles in masonry work, the scale specifically aids in the direct measurement and verification of course heights, which is critical during the construction process.