I agree that both you and I may be able to measure to these limits, but most on these forums are hobbyists and would have little ability to do so !
I dunno', Baron, I happen to know a lot of highly skilled "hobbyists" on this forum who are capable of doing professional level work so let's agree not to go there, okay? We wouldn't want to offend anyone.
I certainly couldn't define tool life in those terms, not that I would be bothered about getting an extra dozen cuts from a tool that I may only use infrequently. I generally aim for accuracy of a thou or better, so a tenth is neither here or there.
The point was that the accuracy of the tool holding system matters with regard to tool life. It's pretty well established and accepted throughout the industry and is certainly something even a hobby guy should be aware of, so I raised it.
This has absolutely zero to do with the level of accuracy the user is working to. I don't know how to make this any clearer for you, Baron.
Have a look at the tips of the teeth of an end mill. See those little hooks? Typically, the wear you see is not even. One or possibly two will be worn more than the others and this definitely affects the function and accuracy of the tool. That asymmetric wear is an indicator of run out in the tool holding system, and you can be sure this extends to the sides of the end mill as well. How much of an impact this has on tool life, finishes or accuracy depends on the amount of wear that exists. In a hobby shop, tool life may be longer than in a pro shop but shorter life is shorter life as far as I'm concerned.
Your ability to measure how much run out there is or the accuracy levels you aspire to or even the amount of spindle run out the machine has are separate issues that have nothing at all to do with the fact that the more run out the tool holding system induces, the more asymmetrical wear there is and the shorter the tool life will be. That is what the collet makers are pointing out. I was doing the same thing. It is not "rot", or BS as we say on this side of the pond; it is fact.
We come from different cultures. Quoting something someone says and labeling it as a "load of rot" may be acceptable in your country but it will be seen as an insulting challenge here. Just some friendly advice.
As for me, in light of the above consideration, I decided not to be offended. Life is too short for that sort of thing.