So, how do you avoid mistakes during application? Ensure the spreader is calibrated correctly and ensure the application has the correct overlap.
Purdue University Turfgrass has both topics covered.
First - Fertilizing Existing Turf by Zac Reicher and Clark Throssell
Second - Spacing Between Passes of a Rotary Spreader by Zac Reicher
Go to j-dturf.com to learn more about J&D Turf.