The following is relevant to Logistics/General Workshop only
Going to speculate that the selection we provide can be rather coarse as the primary use case is drilling pilot- and through-holes in wood for common lag screws and bolts. #6, #8, #10, #12, ¼", ⅜", ½" probably a strong - if not overwhelming - majority of what you’re going to see hand tools used for.
It’s good to have other sizes for general use, but that strikes me as extremely low priority. If they’re included in variety packs, cool, we’ll stock them since those seem to have lower unit costs than buying individual sizes.
Edit: Accomodating #4 and #20 lag screws (~5/16") :
| Number | Dec Dia | Cloest Frac Dia | HW straight | SW Straight |
|---|---|---|---|---|
| #4 | .112" | 7/64" | 5/64" | 1/16" |
| #6 | .138" | 9/64" | 7/64" | 3/32" |
| #8 | .164" | 5/32" | 1/8" | 7/64" |
| #10 | .190" | 3/16" | 9/64" | 1/8" |
| #14 | .242" | 1/4" | 11/64" | 5/32" |
| #20 | .320" | 5/16" | 15/64" | 7/32" |
… we could focus on the following sizes, adding ⅜" and ½" as through-holes for bolts.
| Frac | Dec |
|---|---|
| 1/16" | 0.0625 |
| 5/64" | 0.0781 |
| 3/32" | 0.0938 |
| 7/64" | 0.1094 |
| 1/8" | 0.1250 |
| 9/64" | 0.1406 |
| 5/32" | 0.1563 |
| 11/64" | 0.1719 |
| 3/16" | 0.1875 |
| 7/32" | 0.2188 |
| 15/64" | 0.2344 |
| 1/4" | 0.2500 |
| 5/16" | 0.3125 |
| 3/8" | 0.3750 |
| 1/2" | 0.5000 |
In my experience, there will be high breakage rates on 1/16" through 1/8", moderate breakage rates 9/64" thru 15/64", low breakage rates 1/4" thru 1/2".
Not giving consideration to metric because in my experience metric lag screws and bolts are vanishingly rare at hardware stores and wood doesn’t demand the tolerances of metal.