This is based on zero evidence, and is only my personal view point. I think the chance of being inspected probably drops a bit. There are a fixed number of customs workers, and increased number of packages. The chance any individual package gets inspected would drop slightly.
However, this may be offset by an increased chance of a package getting lost. If the number of packages increases, it may increase % of packages being lost. At the end of the day, I think your chance of it being lost or inspected is very low.
You have to go into the purchase knowing there is a small chance that you won't receive it (due to loss or customs seizure).
