Eight minutes, and the same eight every week.
Five short tasks in a fixed order: a mark to answer, four marks told apart by place, arrows to read past, a sequence to hold, and six patterns to finish.
Once it starts it runs to the end, so give it eight uninterrupted minutes somewhere quiet. What comes out is a baseline of your own — five figures that mean something beside your other weeks and little on their own.
This one goes into the record.
A single reading is mostly noise. Once there are about five, the ordinary swing from one week to the next can be drawn around them, and a fortnight you remember as foggy usually turns out to sit inside it.
The readings that fall outside the swing are the ones worth a second look.