Constant phronesis_runtime::EPOCH_DURATION_IN_BLOCKS

pub const EPOCH_DURATION_IN_BLOCKS: BlockNumber = _; // 600u32

This determines the average expected block time that we are targeting. Blocks will be produced at a minimum duration defined by SLOT_DURATION. SLOT_DURATION is picked up by pallet_timestamp which is in turn picked up by pallet_aura to implement fn slot_duration().