firefoxfey did so and mentioned it on one of the recent question-and-answer entries in 
lj_feedback).
Some "personal" journals have hundreds of posts per day, though most of these seem to be automatic feeds of one kind or another (and at least a couple of journals seem to have had all their entries (re-)posted overnight).
The top ten "personal" journals from the last day-and-a-half seem to be:
| 252 | mparent7777 |
| 238 | brianben |
| 221 | rokokoko |
| 217 | zettor |
| 213 | gambibi |
| 211 | kdnlr |
| 210 | iwanttoreadthis |
| 209 | ianeer |
| 197 | kibalchish |
| 195 | temnnik |
The top ten communities are:
| 421 | proanorexia |
| 369 | sgsale |
| 315 | statements |
| 181 | maginfo |
| 127 | mp3_share |
| 123 | rq_version3 |
| 118 | thequestionclub |
| 118 | ru_politics |
| 110 | madradhair |
| 109 | web_obzor |
You have to wonder how some people have time to eat or sleep. (ohnotheydidnt scored a disappointing 87, by the way.)