Terry, inspired one of your recent swims I finished off a swim practice with 4 x 25 focusing on progressive breakout skills trying to maintain that speed for the length.
#1) Streamline pushoff, no kick, breakout level with the water and begin stroking
#2) Pushoff, one light UDK into breakout
#3) Pushoff ,one strong UDK....
#4) Pushoff , 2 firm UDKs to breakout
How fun that was! Usually the first length of a set I have a great underwater pushoff with possibly one kick. This simple exericse is a great way to progress to multiple streamlined pushoffs with 2 or more kicks in a row as a way to drop time.
Without changing anything else in my stroke, the remaining length after each progressive breakout dropped by about a half second each. A potential 2 seconds per 100 savings after just 100 yards of practice is in sight.
The areas for improvement are everywhere, but often we are neither looking in the right place, nor focusing attention on a specific aspect and simply "hoping" it gets better.
I've done a lot of streamlined pushoffs no kick, and a lot of UDKs as far as I can go underwater, but have never practiced one or more UDKs as part of a breakout strategy for a short swim.