My high school was solidly mediocre, which meant it had basically nothing to challenge me. I don't say that to say "hey look how smart I am" but rather to say that the school lacked the means to challenge students at a variety of skill levels, so if you were at the wrong ones, high or low, you lost out. Everything was calibrated for the C-student, pretty much. Aside from having the option to take algebra/geometry/trig instead of "math 10-12", and a couple optional science classes, there were no choices for the college-bound. (There was a strong vo-tech program, and there was a "business track" to train secretaries. I kid you not.)
So anyway, when I was in, I think, 10th grade and we were offered the chance to take a national aptitude test just to figure out where we were actually stronger or weaker, I took it. It reported results in six broad categories. In five of the six I was 99th percentile, so that didn't help and I don't even remember what the categories were.
In the sixth category I was fourth percentile. The category was "clerical speed and accuracy". The test consisted of pages and pages that looked like this:
Line after line after line, no spaces. The task was "count the 'O's" and it was a timed test. The score depended on both how many you got right and how many blocks you got through. (Just to be clear, this was a paper-and-pencil exercise. No search. :-) )
I thought of this today during one of my most-loathed tasks for our team's documentation releases: the "production check". Everybody on the team is given a slice of our (very large) HTML documentation set to "proofread" before publication. The instructions actually say "proofread", like I could possibly read all that in a day or even two. (And have I mentioned that our team is half the size it was a year ago?) I scan each page looking for anything that jumps out, like weird formatting or bad headings or suspicious syntax blocks. I spend more time on parts that have been heavily modified since last time (I can haz source-control logs), but it's still scanning. Meanwhile, my wrist is unhappy because the navigation requires lots of mouse-clicking, and I wonder how I could make it more keyboard-driven but never solve that. (There's a multi-pane focus-grabbing thing I don't know how to solve.) But mainly, my eyes start to glaze over after a while. And all I can think of is that this isn't so different from "CCCCCOCCCCCOOOCCCCCOC" after a few hours.
Fortunately this only happens four times a year, for a day or maybe two. The rest of the time I can get out of the fourth percentile. Maybe even into the 99th.