The powder applies much differently than spray does and as such, there is a point where you could be applying too much powder. While it will depend, and vary on the effectiveness of a particular powder, there is a general rule of thumb that you can abide by. For most powders, they will perform well when you lightly coat the bottom of your shoe. You can easily get caught up in the notion that you must completely saturate your shoe to get the full effect. However, there is a reason why you want to avoid that with powder.
What happens is the powder begins to clump up and when you see this happen, it signifies that you are using too much of it. Thankfully, it is really simple to fix this issue as you merely need to hold back the amount you are using the next time you apply it.