The Matter of Deadline Wording
The deadline was originally described as 'end of week.' It has since been described as 'by Friday,' then 'by Friday EOD,' then 'by Friday EOD latest.' The date has not changed.
Monday's email said: "by end of week, that would be great."
This was a request. It contained the deadline (end of week), the item being requested (this), and an expression of preference rather than urgency (that would be great). The tone communicated that end of week was the desired time and that deviation was possible.
The recipient read this as: sometime before Friday, probably Thursday would be fine.
Wednesday's email said: "Just a reminder that I need this by Friday."
The word "just" softened the reminder. The word "need" replaced "would like." The deadline was specified as Friday rather than end of week. The communication was the same deadline, more precisely stated.
The recipient read this as: Friday. Still okay.
Thursday morning's email said: "A quick reminder — I need this by Friday EOD."
EOD had been added. EOD specifies end of business day. The deadline was the same deadline, now with an intra-day precision that had not previously been required. The word "quick" still softened the reminder.
Thursday afternoon's email said: "Please send this by Friday EOD at the latest."
The phrase "at the latest" was new. "At the latest" is a phrase that means: this is a hard deadline, there is no later. The same deadline that was introduced on Monday as something that would be great had become a hard requirement.
The task was completed Thursday evening.
The deadline was Friday. It was Friday the whole time. The language got more serious as Friday got closer, not because Friday changed but because the sender's relationship to Friday changed.
This is how deadlines work. The date is an anchor. The language is the tide.