Suspicious in that it's only twice a month? When my kid first started preschool, we got exposed to all sorts of wonderful novel viruses, and I had respiratory infections of various sorts for probably 50% of the days for the entire autumn and winter. Most of them not rising to the level of high fever and not being able to work, but definitely noticeably cutting my productivity.
(Child spent 16 % of the year sick. Across two parents, that is nearly a month of absence in a year.)
"A cold" doesn't usually totally incapacitate someone working from the comfort of their home, down a paracetamol, drink hot liquids, take a nap, don't need to be 110% productive but still can manage to get some job done. But "a massive hangover" is something that surely can knock someone out.
Sure, this never happens. Literally, noone in the history of mankind has gotten wasted in the middle of the week.
A cold can absolutely do that. Expecting people to work while they're sick is an unhealthy work culture, don't inflict that on other people.