yes. I may have to do this
As an adjuster in Des Moines, I know there were areas of Johnston that did get hail last summer/fall which came from the west with high winds. A lot of the roofs I looked at had damage to west slopes mainly.
In regards to tear off, keep in mind if you just keep adding layers of shingles, not only are you decreasing the life expectancy, but the roof framing itself is designed to support ONE layer of shingles. If you live in Johnston, tearoff down to the sheathing and ice and water shield is city code.
I've been on more than a few roofs that have 3 to 4 layers with some having the bottom layer as cedar shakes. The insurance companies will pay for the additional tear off in those cases because of the concern with roof collapses.
If you have 4 layers and a heavy snow load some winter...look out! Especially if we get an ice storm that drops tree branches onto your roof.
Laminate (architectual) shingles are basically the norm now...and I agree, if it says it has a 30 year life expectancy, you're doing great if you get 20 out of them...