When I started running in college I ran at over 200 steps a minute. I had great recovery in my stride but I'd always drop my foot right in front of my body.
Once I started bringing my knee up (first goal coach set out for me), I had to lengthen my stride (increasing my push-off power) in order to continue to land with my foot under my body. This brought my steps per minute down to ~184 which is where it is today, and increased my efficiency greatly (ultimate goal coach set out for me).
For me running with a longer stride and less steps made me faster, for this girl it'll depend on where she's starting from. With that I'd like to add than many high school coaches tend to operate under the assumption that a longer stride ='s a faster runner regardless of who the athlete is. This is a mistake, just as believing that a shorter stride will make any athlete faster. The goal shouldn't be a longer or shorter stride, but a more efficient one.