For me, when I find a hot lure/bait. If I did not buy enough of them the first time I bought them and buy more at another date, I will never catch another fish on that "hot bait". If it is worth buying 1, then sure must be worth buying at least 4.
I don't have a hot bait that is best year round in all conditions. Mine switch regularly. That's what keeps us spending $$$ .