Body by Science recommends not doing sprints for two days before or after a strength training session. I have been doing the strength training once every seven or eight days so I only get one or two thrashes on my rowing machine between them. I am noticing an improvement each BbS session so I am happy at that. They state that the body takes five to fifteen days to fully recover and if there is no improvement the reason will be either too frequent training or one has reached ultimate strength. I am away for a week next week and when I get back I will up the frequency to once every five days with one speed session in between each and see if I am still improving. If not, I will drop back to what I'm doing now.
Why use a sledge hammer to crack a nut when a steam roller is even more effective, and, is fun to drive.