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[Disclaimer: I'm not a mechanical engineer, or even a choo-choo train engineer. I do manage system engineers, but computer screws are tiny, tiny. However, I did do 30 minutes of Google research, so I am a qualified expert.] First off, the fasteners you mentioned are not what I would consider critical applications, as they are not subjected to high cyclic loads (for example: rotational like con rods, or heat/pressure like cylinder heads). They are primarily vibration and shear loaded, and failure would result in noticeable vibration or noise, not a life-threatening condition (unless all your steering bolts failed at the same time--not likely). Second, empirical data (years of wrenching on several cars, motorcycles, bicycles, etc., etc.) and 30-minutes of scientific research point to lack of proper torque (i.e. too little) as the primary cause of fatigue failure resulting from excessive load cycling. Over-torquing, on the other hand, does not appear to be a significant factor in fatigue, though it can be a cause of tensile failure (see links for more on that). Third and lastly, torque is notoriously overrated and poorly executed. What you actually need to measure is clamping load, but there are few ways to do that accurately. One notable example is connecting rods, which specify a stretch value to more accurately measure clamping force. In their case, torque is at best a ballpark number. Unless you meticulously clean bolt and nut threads, apply proper lubricant, and make certain you are using the correct dry or lubricated torque value (and not vice-versa), your torque reading is most likely off by a considerable amount. Grit, friction, and oxidation all reduce the effective torque value (a higher percentage of the measured force is being consumed in overcoming friction vs. clamping down). The included links from Fastenal point to an expected 30% variance in measured vs. actual torque. Ft-Lb to Nm conversion is ~35%. Therefore, your error in measurement would result in anywhere from 5% to 65% over-torque, with a bias toward the low end based on all the factors that can cause under-torquing. So if you didn't feel the bolt "give" and suffer an "Uh oh" moment, they're probably fine. If you did, well then you're probably screwed. I mean bolted. Time for me to go on YouTube and do some more scientific research. References (there may be better ones, but these are free): Bolted Joint Design - Fastenal
Fastener Fatigue - Fastenal
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