+1. I was not aware of the 'stickiness' of the wal pragma. Thank you for the tip. I will be defaulting to this going forward. For a quick confirmation, I used:

  $ f=$(mktemp)
  $ sqlite3 $f "pragma journal_mode"
  delete
  $ sqlite3 $f "pragma journal_mode=wal
  wal
  $ sqlite3 $f "pragma journal_mode"
  wal

Edit: struggling to format code markup correctly on my mobile.