I plant then water just a little were the roots should be. Water again when the soil is fairly dry. if I water to run off is because im not as meticulous as I use to be. I would say if you are watering to runoff with a seedling in a large pot you risk overwatering. I never tried to rescue overwatered seedlings looks difficult. It happens, its ok just be careful how much love you showing.How do you plant your seeds as well. Do you water pot until you see run off, then plant seedlings?