Came up with 20 seconds per 25, 41 seconds per 50 (poor open turns). That is compared to the 50-54 seconds per 50 I was swimming last week trying to lower my stroke count//

It is only a fair comparison if you had the same HR during each swim. Now probably you cannot get as high a HR with slower turnover, but good swimmers can do this to compare apples to apples. That is why you see most good swimmers taking 10/11/12 strokes per lap in SCY distance events..