UTIs on a Friday
In my day they were PWIs (Preliminary Warning Instructions) - and, yes, it usually took 3 or 4 days to investigate an incident (which usually included stopping the "starred" staffs jumping to conclusions), determining the fix and penning the instruction. This meant that the end of the week was normal and such instructions were referred to as the "Friday PWI". In those days of course, there were enough experienced engineers in blue suits etc to keep it down to 3 days or so.
Sadly....I am not sure that is still the case.