Function check_delayed_command_queues 

pub fn check_delayed_command_queues(
    queues: Query<'_, '_, (Entity, &mut DelayedCommandQueue)>,
    time: Res<'_, Time>,
    commands: Commands<'_, '_>,
)

The system used to check DelayedCommandQueues, which are usually spawned by DelayedCommands. When the elapsed time exceeds a queue’s submit_at time, the contained queue is appended to the system’s Commands.