I often implement numbered list for both print and web projects. At times it is just more efficient to break the list into two, three, or four columns.
How should item ordering be handled?
Should numbers start at 1 in the top left then move down the column, then jump to the next column to continue numbering? (Option A)
Or should numbers start at 1 in the top left the move sideways to #2, #3, etc., jumping columns for each number? (Option B)
In terms of web responsiveness, Option B provides better break points (at times with 3 or 4 columns).
Should this be handled the same in both print and web?
I think that your first option is a much better practice. I wouldn’t treat a numbered list any different than I would design an alphabetical list. Would you setup a book’s index in an alternating-column style?
Having a reader’s eye scan back and forth across multiple columns doesn’t sell the continuity that an ordered list should provide.
Multiple column text for the web is still touchy, but CSS support is growing (and is in most modern browsers)