State Farm usually includes something as part of your premium to protect your rate if you have an accident in X number of years so you rate might not go up but it still counts against you and will show up if you shop around or if you have another claim.

None of this is correct.

I've got State Farm for multiple cars and home owners. A few years ago they had to pay out about $2500 for something I had almost nothing to do with. Longer tangent explanation and never mind the detail for now. I've been getting discounts for multi-policy, multi-vehicle and accident free for years, not paying any sort of fee for accident forgiveness - at least not anything that gets line itemized on the premium notice.

What I was told by the local agent at the time: any vehicle continuously insured by them for (8) years automatically gets accident forgiveness. There is a limit to the number of claims over some period of time that this applies to. At least (2) claims, I think maybe (3) and I don't remember the size of the window. Didn't get in to how long after exceeding that number it takes to get the forgiveness back. I did verify that the forgiveness thing is tied to the vehicle and not the policy or driver. After they made the problem go away my premium didn't change at all and it's the last I heard of it.

My girl has Progressive on her driver and last year she had a parking lot bump with a friend of hers. The quandary was to just pay it out of pocket and avoid the insurance company hassle or file the claim and roll the dice on the premium bump because it was like a $1200 quote on whatever she backed in to. Oddly enough, hardly a scuff on her car but nevermind that too. As with most insurance web sites, the progressive one was completely useless for searching for the fine print. What I did come across was some Pennsylvania state insurance regulations. Bottom line being that in PA the insurance companies are not legally permitted to raise your rates until they pay out X number of dollars over Y number of months for claims. Whatever the dollar limit it was higher than the claim at hand so again, they made the problem go away and no premium changes since.

Your mileage may vary and objects in mirror may be doing something totally stupid.

Any idea how it works with comprehensive claims (do those make my rate go up?)

Last year I had two vehicles damaged by a severe hail storm, and a month ago I hit a large armadillo (with a third vehicle) at 55 mph, which caused $2400 worth of damage to the front air dam, fog light, brake cooling ducts, etc. I was only out the $100 deductible... so far

No they don't. You have to pay for that. I explained this in my first reply in this thread.

What you said in your first reply is exactly what I meant.

So, considering all this
and the benefits of paying less than X $ damage amounts out of pocket yourself,
at what time period ( or vehicle resale value) should all collision coverage be dropped?

When a new vehicle is 3 years old, 5, 7 etc?