Okay, transcribed the sizes from Machinery’s Handbook into
https://wiki.shapeoko.com/index.php/Tools:_Screwdriver#Fasteners
and the even gradation of sizes makes it obvious why the chisel-shaped screwdriver blade became a standard — it facilitated tables such as:
which allowed one to use 9 sizes of screwdriver to drive 24 sizes of screws.
Got a little further along on the Brownell’s bits, and will hopefully finish those up and some other sizes presently, and before I get bored with this, work up one unified, sortable table which will allow me to purchase a set of bits which are nicer than the ones I bought in a Wheeler Engineering gunsmith set, and more generally useful.
As much as I’d like to just buy a set of matching Brownell’s Magna-Bits, I’m probably going to draw the line at a full set of metric sized screwdrivers to carry around — eventually I’ll get the Chapman’s Master Set, and when I retire, the Brownell’s — until then, I did indulge in:
http://www.graceusatools.com/item-details.php?item_id=103&category_id=1
which I’ve added to my traditional woodworking tool chest.