Technically your 3 day limit is 44 hours, flying or duty.
The hours can be big, in bursts. If you stay legal. Bigger if you do not.
I suspect there will not be too many big houred Ag pilots in the current generation.
For the same reason as in the rotary industry.
Hill country spreading can generate 200 ton a day.
Not so cropping work.
Spraying... dawn till dusk is for lightweights....
Hope this helps.