Can Pind Daan be done only once or should it be done annually?

Pind Daan at Gaya Ji is usually done once in a lifetime for each departed soul. However, annual Shraddha and Tarpan should still be continued every year, especially during Pitru Paksha. If one forgets to do regular Shraddha, Pind Daan at Gaya can compensate due to its powerful effects. It is also common to do it for ancestors who passed away generations ago and were not given proper rituals.