There is a very advanced strategy known as "veil confirm" or "veil scrying", where it relies on the Shimmering Veil breaking or not breaking on a given cookie click amount to predict RNG in the Grimoire to some degree, since Shimmering veil breaking or not breaking on a given click is seeded. However, this strategy works best when the breaking chance is 30% as it maximizes the probability of Gambler's Fever Dream yielding Force the Hand of Fate on an ideal seed. In any case, if you are active (which is generally considered far superior to idling), Shimmering Veil is largely useless, so you might not want to buy it either way to save heavenly chips.