Holding the magnet over the nail polish for longer (last time I think I just did about ten seconds!) definitely gave a crisper more pronounced pattern which I really like. The pattern did spread a bit over time, even once the polish was dry, but it was still a good distribution of the colours. I finished off with as layer of holographic silver glitter. I made sure not to paint it on too thickly as I wanted the pattern underneath to remain visible.
This took minimal effort and I love the end result. I kept finding myself moving my nails around to look at the gorgeous colour shift, especially in bright light where the glitter would shift too!