During regular sprints, the individual moves at a fast rate. This means that it is difficult to notice any issues occurring but it is also difficult to try and fix those issues due to the individuals wanting to go all out and move without resistance.
A sprint is an absolute speed exercise, this means that there is a high requirement of velocity with low to no external loads. If individuals compensate in a certain way, you want to identify if it´s a motor issue or if the person lacks strength/stability in a certain area.
If it is a motor issue you can jump straight into this progression if it´s a strength/stability issue I would advise you to start fixing that and then jump into this progression as individuals can not expect to build certain muscles and then expect these muscles to flawlessly co-operate with each other.
Exercises that improve, ankle, hip, core stability should be done in an isolated manner to ensure individuals have built sufficient time with them. Then we go over into more ¨functional¨ exercises. This principle makes increases the efficacy of one’s practice because he or she can now to learn how to use the muscles effectively, with compound exercises it is more difficult to feel the intended muscles because there are always multiple muscles involved. The sprint is a compound exercise, with a lot of muscles working at the same time.
Considering an individual has a motor issue the first step I would go to is to try the sled push with a heavyweight. For increasing sprint speed, the most optimal loading ranges between 0-30% of body weight on the sled. I would start at 100% of bodyweight on the sled for that individual and make them train absolute strength (the opposite of absolute speed) with the sled. While they are doing absolute strength work I would ensure proper joint alignment and fix the issues that they had with the regular sprint.
Once they have shown competency with the slow contraction, we progressively lower the weight. During the progression, it is vital to make them earn the next step back to a normal sprint. They need to show that they can execute with the right mechanics at each step of the way.
The duration of this process really depends on the individual, we can absolutely not say that it should take x amount of time. Factors like: motor control, age, training age, movement error age, if it´s a minor or major error, all have a lot of influence on the duration it takes to fix it.