Eye-Bo is only a supplement, and its effects can be felt more in the long term through persistent use. How fast people get "results" is subjective. Some are already good at visualising and just need a little push, while others are not very good and need much more entrainment and practice to become as good at visualising. Some are very sensitive to rhythmic entrainment, while others are more resistant. Some can focus on the same thing for long periods of time, while the attention span may be lacking for others.
Compare a guy that loves to draw, finds music very emotionally affecting, and can focus on things for hours at a time, to a guy that comes up with very few ideas, spends the majority of his time being stimulated by various external mediums like movies or video games, and can barely hold his attention onto something before it becomes boring. Whom do you think will feel the strongest effect of the entrainment? Many factors decide how much of an effect it'll have on you and how much you'll have to use it in order to get "results", which is why that, while testimonies may be fun to read, they're ultimately irrelevant.