Disavow File - without a manual penalty - is it needed or not?

Selected answers from the Dumb SEO Questions Facebook & G+ community.

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  Patty Mantaloons: I use it as an insurance policy, just in case a link profile gets dirty somehow, I can show I`m being proactive
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  Dan Thies: Yes. The cost of maintenance vs trying to build one after the fact argues for Yes, but we also can`t say that it`s not being used. The script is flipped a little with Penguin but other not-Penguin-things can still use it. Today or tomorrow, as long as Disavow exists.
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  Rishi Lakhani: Yes
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  Roger Montti: Disavowal Report Expert has got to be the easiest SEO job in the world. Way easier than building links or making recommendations for improving a site.
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  Michael Stricker: An ounce of prevention is worth a pound of cure. Why wait to suffer through a manual penalty?
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  David Ogletree: Yes
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  Jim Munro: I think so.
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  Jim Munro: I think it`s worth considering the history of the disavow file when evaluating outcomes. Google flat out lied when the disavow link was first offered. It wasn`t connected to anything, It did not do anything, except act as a reference during a manual action review. It was just a repository to accept and store files. This was still the case when Brian White appeared at SMX Sydney in 2013. So case studies from that period should be weighed with that in mind.
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  Ammon Johns: I`ve never needed one unless the site had very good reason to be expecting a penalty. There`s evidence of sites removing the disavow and actually increasing ranking
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  Jim Munro: The first thought from the recent case study offered by Ammon Johns , above, might be that this site might be setting itself up for a downturn sometime in the future. I have two long-established sites both crippled by Penguin, victims of negative seo, one with a disavow file and another from which the file was removed. I still can`t figure it out. :)
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  Roger Montti: How come the people who answer yes to this kind of question consistently never mention all the actual good the disavow did for them? Like, "yes, I did X and it resulted in Y and Z." Ever notice how the answer is often, "Yes, I did X" and that`s it? In actual fishing, a photo of a fishing fly someone made can get the maker a pat on the head. A photo of the same lure hanging out of the mouth of a fish it caught is far more meaningful. So please follow up with what good those Disavows did for you or your client.
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  Neil Cheesman: Does Disavow do anything? (if not in a manual penalty) or does it remove link(s) from the equation if they are poor quality links - but then IF poor quality link(s) is/are not in the Disavow then it/they will be picked up and `not counted` anyway... which seems to beg the question - if not in a manual penalty, what is the point of the Disavow file? Is the Disavow a quicker way for those potentially poor quality links to be evaluated - or leave and let the algorithm deal with them?