Could be strain dependent; I got a BlueJay cross from a Toronto local that the seeds were just ridiculously large and burly and the seedlings grew very big very fast in the same tray as an 'elite' strain that was smaller seeds and grew very delicately. Plus some strains are simply better suited to artificial lighting.
FYI seeds are considered 'good' for 5 years and then the grem rate starts to decrease.