Arbitrary day-of-the-week and date-based deadlines piss me off so much.

I worked for a person who had a fixation on "neat" deadines: the "first of the month", "the end of the week", "the start of the quarter", etc. It'd be one thing if the dates were tied to legal compliance (tax filings, etc), but that usually wasn't the case. They were chosen because they were "tidy".

I'd time meetings looking to maximize time for work. You try to meet late in the day Wednesday because an early Tuesday meeting might get an "end of the week" deadline. A late Wednesday meeting was more likely to garner a "end of next week" deadline. Meeting Thursday or Friday guaranteed an "end of next week" but you lost Thursday and Friday work time. Wednesday was a gamble, though, because it was still early enough to get you an "end of the week". Meeting after lunch helped with that.

You always had to be aware of the numeric calendar day, though. Gunning for an "end of next week" deadline when next Wednesday was the end of the month (or worse, end of the quarter) almost guaranteed you an earlier deadline than you wanted.

All of this deadline-setting happened with little regard for the amount of time work was going to take.

It was immensely fun, when setting a deadline in this person's absence, to get a group to agree on a mid-week deadline. You could see it make this person's skin crawl hearing that the work would be done on Tuesday or a Thursday.