We don't need to poo pick as there is enough pasture to move the horses around. When they move off 1 field, it is chain harrowed and rested. I know there is some question abour whether this adds to a horse's worm burden but we have a good, compulsory worming programme and have never had any trouble.
i didn't when i had lots more grazing, but now i've got 4 on about 7 acres i poo pick 2 x daily, when i feed them. must admit, it's really therapeutic, and there's something so satisfying about knowing the fields are immaculate and the worms are kept to a minimum.
I poo pick the pony's summer starvation / strip grazing paddock but leave the big fields (used for my competition horse and winter grazing for the pony) with the poo in because they are very large fields which don't get over-grazed. The big fields are harrowed and rested every couple of months.
poo pick daily. Pony on starvation paddock and 2 horses on 4 acres which isnt rested or rotated so have to keep it well maintained e.g. fertilised and topped.