Depends on how the stride length is being achieved. Is it a natural foot landing or is it being forced? Overreaching and tring to increase the rate isn’t going to improve things. The stride length has to be appropriate for limb length and current strength levels and both frequency and stride length will improve together initially. Eventually, stride length will optimise and then frequency will be the route to further improvement but that occurs at a pretty high performance level.
There is a detailed description of Ben’s technical change from 10.30s to 9.79 in the fiirst Forum Review if you want more detail on this topic.