Sure. The piece of advice being offered is a potent one: "Any time you come up with a significant plan, assume the worst about your own planning and your own performance. Specifically, reformulate the plan and your expectations of its execution in terms you would find insulting." If someone were to take this seriously, it would dramatically change the way they live. Much in the same way that the corresponding epistemic pessimism is supposed to, and I assume that's your intention.
So, again, potent medicine. At the heart of your argument for doing this is what looks to be an empirical claim: "In general, following this advice will give you an accurate picture of your probable performance." This may be so, but it seems likely to me that the relationship between expected and actual performance will vary significantly from person to person. And if in a given case your claim is off the mark, the effect could easily be harmful.
So, I wondered if you considered this an empirical claim. And if so, whether or not you had some relevant data. If you don't have any relevant data, and you do consider this an empirical claim, then it may be a bit rash to offer this kind of advice.
Yes, I consider this an empirical claim. I have a fair amount of anecdata from people I've shared this with in person about this being a useful approach.
That said, I agree that some may not find this effective or will find it harmful; this is why I wrote "in many cases" rather than "in almost all cases" or "you will find" or similar.
If you do not find this technique effective, I suggest that you don't practice it. I and a few friends found it useful and interesting enough to be worth disseminating.
One good way to ensure that your plans are robust is to strawman yourself. Look at your plan in the most critical, contemptuous light possible and come up with the obvious uncharitable insulting argument for why you will fail.
In many cases, the obvious uncharitable insulting argument will still be fundamentally correct.
If it is, your plan probably needs work. This technique seems to work not because it taps into some secret vault of wisdom (after all, making fun of things is easy), but because it is an elegant way to shift yourself into a critical mindset.
For instance, I recently came up with a complex plan to achieve one of my goals. Then I strawmanned myself; the strawman version of why this plan would fail was simply "large and complicated plans don't work." I thought about that for a moment, concluded "yep, large and complicated plans don't work," and came up with a simple, elegant plan to achieve the same ends.
You may ask "why didn't you just come up with a simple, elegant plan in the first place?" The answer is that elegance is hard. It's easier to add on special case after special case, not realizing how much complexity debt you've added. Strawmanning yourself is one way to safeguard against this risk, as well as many others.