This is kind of like the last one.
1,2,3 sec drill
Swim a length with a 1 sec. glide,then a length with a 2 sec. glide then one with a 3 sec. glide.Time each one and put the same effort into each pull and kick.What do you notice.Is the 3 sec glide OK or much worse.If much worse you need to work on your streamline &/or kick