My wife and I recently came across this sign on the front door of a medical facility where we had an appointment. If we are obligated to follow these instructions, we must attempt some other means to gain access to the building.
No doubt when the creator of the sign wrote it, they didn't think that the words "at all times" are an absolute, and leave no exceptions. In life we often encounter absolutes tossed about when they shouldn't be: "they always lose," "this always happens to me," "you're always late," "you never ..."
When we write instructions, we should be careful that the words reflect our intended meaning: that we don't say too much, nor too little.
The Global Investment Performance Standards (GIPS(R)) occasionally uses absolutes, when in reality they're not meant. For example, we know that "all actual, fee paying, discretionary portfolios must be included in at least one composite." But we also know that there are a few exceptions to this rule (e.g., portfolios that are excluded because of significant cash flows, because they've fallen below the minimum, because they haven't been managed long enough, because they're transitioning from one composite to another).
Almost 40 years ago, when I was stationed in Hawaii with the 25th Infantry Division, I had the "extra duty" of being our artillery battery's race relations officer. One of the things we would tackle was prejudice, which is typically built around absolutes: "all black people ...," all Jews ...," "all whites ...," "all Hispanics ..." In reality, we know that the "all" never applies to any group. There seems to be plenty of evidence to support avoiding absolutes, in just about all areas of our lives, unless they really apply ("never do illegal drugs" would be an example that I think does work).
The words we use count. My wife and I have become fans of The Big Bang Theory, and Sheldon is great at dissecting the words people use (I'll confess that I am sometimes guilty of this too; an example: when a waitress tells you, "if you need anything, my name is Mary," might cause one to ask, "what's your name if I don't need anything?").
After conducting verifications, I want to make sure my feedback is clear to our clients. Sometimes I find myself writing "you should ...," when "you must ..." is more correct. I generally refrain from telling someone things they must do, but the reality is that to avoid confusion, such wording is sometimes needed.
Someone once said that there's no such thing as writing, just rewriting. This applies to everything we write, whether it's emails, letters, reports, or the words that are to appear on signs. Even blog posts!