I don't know for me I rather have that then they taking it on a little college desk where you don't have space for anything other than the test and a pencil.
I do 99% of RC with the highlighter, but just for extra assurance that I don't skim over it I'll quickly note "M.P." in pencil when, and only when, I've decided that I've found the main point. Otherwise, strictly highlighter.
I still can't get over how people show up without any pencils. And that the proctors ask people "Does anyone need a pencil?. I mean really? You didn't bring even 1?
My Scantron sheet says "use black No2 or HB pencils only", so I'm guessing they are similar enough. The common wisdom of the internets seems to be that a "middle of the scale" HB is pretty much a 2, but none of the scales are truly standardized.
I am a pencil sharpening nazi.. went though ... recently purchased the best pencil sharpener I've ever used ...
Staedtler® Double-Hole Metal Pencil Sharpener