On the a/c I fly (B 737 - 800) the Ditching Checklist seems to be very much for a premeditated ditching - a throwback one suspects from the days of large piston engine a/c flying across the pond where you might have to shut down 2 of the 4 engines on the way across and then not be able to maintain height. You then had 20/30 minutes, maybe more, to prepare the cabin (brief pax, don lifejackets, get the dinghies out) and on the flight deck do all the necessary items.
I would suggest (as this incident proves) that most ditching these days are unpremeditated or virtually so. Maybe we need a much shorter checklist for this eventuality just listing the essentials. (The Boeing checklist says burn off fuel to minimum - hardly applicable in the Hudson incident).