I recommend having one person place the infill. Having multiple drop spreaders may lessen the perfection of placement.
When you have accomplished placing and brushing in the first lift, it is time to change direction and cross the existing pattern.
(Like the image to the left). Place another 10 passes (5 up & 5 back) or more to achieve placing 1/8” to 1/4’” of an inch of infill placement. Keep track of how many runs/passes that will give you 1/8” to 1/4” prior to brushing the second lift. It may be 12, 15, or even 20 passes to gain the desired lift.
*** DO NOT OVERFILL EACH PASS***