www.lesswrong.com/posts/55W4eY9c833NNL62n/empirically-assess-your-time-use?utm_s...

This line is another arithmetic mismatch between the time range and the parenthetical duration. From 7:30 to 11:30 is exactly 4 hours. The post instead labels that block as "3.5hrs".

The LessWrong page itself shows the interval as 7:30-11:30. A standard time-duration reference confirms that a period starting at 7:30 p.m. and ending at 11:30 p.m. lasts 4 hours.

Because the start and end times span four hours, the parenthetical duration in the post is incorrect.

This example line contains an arithmetic error. The stated start and end times are 8:00 and 10:00, which span two hours. But the parenthetical duration says "1hour".

You can verify this directly from the post text itself, which lists the interval as 8-10. An educational elapsed-time source gives the same kind of example explicitly: if something starts at 8:00 and ends at 10:00, 2 hours have elapsed.

So the time range and the written duration do not match; the correct duration for 8-10 is 2 hours.