One egg every other day. The eggs have to maintain a temp of between 98 and 101 degrees constant, (body temp). If the temp of the embro falls below 98 degrees, it will die, ( even when the hen feeds). It's an all nighter for the hen on the nest. Darkness is a turkeys worst nightmare for preditors.
She will also sit there motionless, for hours upon hours, sometimes for a few days, before feeding. One can tell when she has left the nest, because she will be in a different sitting position.