Every execution round should follow with a idle period

[zalmen]

The Poet period should consist of an execution part where the PoSW is executed and an idle period during which the poet will wait for the beginning of the next execution round. The purpose of the idle period is to allow the miners to generate a PoST proof and get ready for the next round of PoET (assuming that a miner will mostly work with the same PoET for many epochs)