Horizontal force during acceleration

During early acceleration (15-20m) should you be trying to exert as much horizontal force along the ground as possible? (as well as full range arm drive)

Later on in a sprint, when you’re nearing top speed I know that excessive horizontal force production can lead to increased ground contact times and bad backside mechanics and therefore vertical force production is more important.

However, during the first 15-20m, will focussing on horizontal push cause increased ground contact and excessive backside mechanics? Or is this not a problem in early acceleration.

I get the feeling that I am too tentative and not providing enough horizontal push during acceleration and therefore limiting my stride length.