Swarming allows you have up to 3 drones in the air at a time per pilot, thereby doubling or tripling your efficiency / coverage. Remeber, drone manufacturers quote you high rates per flight hour, not man hour. When you are in the field, you are working man hours.
Working on one flight hour is approx 1.2 man hours for one drone, for Broad Acre crops, one drone (XAG or DJI) would typically do 18ha per man hour, but with 2 drones that would be 38ha per man hour and 60ha per man hour with 3 drones. Yes, your man hour starts to get closer to a flight hour with swarming due to operational efficiency improving.
The critical parts are your planning or segregation of the field and the pit layout and efficiency of your battery swap out / refilling. They play a big part in your efficiency of the job..
If you can keep to 30seconds to one minute for battery change and refill per drone, and 6 minutes in the air for 2ha, you would get close to 18ha per flight hour per drone.
A Crewed Crop Duster would do on average 2500ha per day (10 hour day) giving 250ha per man hour compared to a drone swarm of three drones giving a coverage of 600ha in a 10 hour day.
We hold swarming approvals for both XAG and DJI for our Ag operations allowing us to have 6 drones in the air at a time with just 2 pilots.