Passage of time

I think qualifiers are needed. To me, just means in the past hour or so.

No I wouldn't, but I would expect that people would be more specific.

"My sister just got married last week."
"My wife just died last month."
"I just graduated yesterday."

When I use the word just, I always mean in the past hour or so.

"I just went shopping."
"I just made a phone call."
"I just typed that letter."

Otherwise I would say

"I went shopping yesterday"
"I made that phone call two days ago"
"I typed that letter this morning."

The only thing with those sentences above, is I always take "just" as modifying the word closest to it. eg: "I just graduated yesterday"--that's all I did yesterday. Didn't fly to the moon; didn't run for president. All I did was graduated. As opposed to "I graduated just yesterday" which means that yesterday, I graduated.

Nitpicky, aren't I?

I use just to mean a very short time ago, or indication that it's the only thing I did.

"I just cleaned that litterbox," works both for time and as a singular act. To clarify, I'd extend either to say:

I just cleaned the litterbox 10 min ago.
I just cleaned the litterbox, I didn't refresh the food dish.

It depends on context, as usual, but that one's not easy at all, because there's the added tense problem:

My brother just died. --> My brother's just died.

Most of the occurancies of "just" less than a couple of hours ago would probably occur together with the present perfect tense, not with the past tense. This doesn't mean that it won't occur with the past tense, though. I've gone through the British National Corpus to check and found a good example:

"He was the one that just died, sir, last Monday." (DM Greenwood, Unholy Ghosts)

(Most of the other finds for "just died" have the perfect aspect, or are cited as general examples; mentioned, not used.)

The thing is: if you dig up something that's not immediately connected to the present situation, you'll usually have a reason. You're explaining something, or justifying a decision, etc. And in these cases you'll link it with "now" through the perfect aspect.

In the quote above, this is not the case. Here, the speaker is invoking something that happened in the past in the hope that the "sir" will remember the event. Perhaps "just + simple past tense" is more common in relative clauses?

[The problem with efficient search for "just" is the "only" meaning. "And then he just died." That gets in the way quite a bit.]

In real life, I would tend to mentally fill in the time gap based on what it was that was just done. "I just washed my hair," would lead me to believe your hair is still wet, it was that recently. But if the setting is a grief support group and you say, "My wife just died," I would take it to mean within the past month or so.

I would think qualifiers are needed. To me, when someone says they just did something, that is fairly immediate, meaning recently, within the last few days or week.

If someone said, I just went to the movies, I'd think they just came from there.

If someone said they were just in New York, I'd think within a week or so.

And talking about crossdressing, that could be within the hour. I don't know when you saw Sam last.

As far as surgeries, I'm willing to give a little leeway. Hospital stays could be within the month because I take recuperation time into account.

I'm with the Sink and the Ferret on this one. It depends on the relative frequency of the action.

"I just washed my hair" means I washed my hair within the hour.
"I just had surgery" means I had surgery within the last month.
"I just got married" means I got married within the last month or two.
"My uncle just died" means he died within the last few months.

When a person says "I just did such-and-such" it means that in his mind it's an extremely recent event. It's subjective. You can't quantify this, people. It's the speaker who defines it.