Are your talking about rocks that slide under motor? Dust just destroyed my motor bearing. Do you block dust from getting in there as well ?

I tend to be too rushed. The cups help. I memorize what goes where and finish within an hour. But I really should be keeping the exploded parts diagram book open for every job. Laying down white paper on the desk really helps me to spot small parts. I have not used the car in a year after I stripped out a rear diff gear and then was focused on rabbits, and desks for the family.