Well of course, all systems are different.
For example if I used a bare bones setup with no startup files, minimal services, no scanners or firewall, then I could shave significant time off bootup. I can get even quicker with SSD boot disks. I've heard one colleague here say their SSD laptop boots up in 3 seconds.
But for that test they likely used a standard off-the-shelf system, no extras but with all normal startup files and services that are generally used, and for the test itself they measured time saving on the system as it performed before using any utilities. That was the benchmark.
So I would assume that they would have found differing results with different systems, but the test is valid as a comparison between utilities.