Contraceptives have a long-standing problem of people being unable or unwilling to follow the instructions, or not catching little nuances like "this pill lasts for 22 hours, so you really need to take it every day at the same time". For a decent-looking summary, see ex. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7533104/ which includes a lot of lines like,
> Hatcher and colleagues report that for both types of pills, the failure rate is less than 1% with perfect use and 7% with typical use.
So no, empirically, it appears likely that people are not capable of understanding "once daily".