It's actually made for every-night use
Take any PM product out of your cabinet and read the small print. Somewhere on the label you'll find the word "occasional." As in, "for relief of occasional sleeplessness."
That word matters. It means the company itself never intended the product for nightly use. Consumer Reports puts the limit at about two weeks. The American Academy of Sleep Medicine says OTC sleeping pills shouldn't be used for chronic sleeplessness at all.
There's a physical reason for the limit. When an outside chemical pushes your brain toward sleep every night, your brain slowly stops doing the work on its own. The same dose does less and less. You take more and more. That pattern is built into the product. It was never a willpower problem on your end.
Sleepwhale started from the opposite requirement: make something a person can take every single night without the dose creeping up. Everything below follows from that.