A well configured and behaved DB should seldom
If it does too often, you should then find out why and try to avoid it.
Testing DB performance while hitting the disk is of little value as you do not want to hit the disk when running live traffic. Disks are an order of magnitude slower.
You should do your benchmarks with traffic that does not hit the disk and if you hit the disks in production you should re-size your system so that you do not hit the disks.