Citation needed.

Read Dan Kahneman's work. He's spent his entire lifetime studying this and won a nobel prize for it too. A good summary is given in http://www.newyorker.com/tech/frontal-cortex/why-smart-people-are-stupid Here's an excerpt:

'as the scientists note, “people who were aware of their own biases were not better able to overcome them.” This finding wouldn’t surprise Kahneman, who admits in “Thinking, Fast and Slow” that his decades of groundbreaking research have failed to significantly improve his own mental performance. “My intuitive thinking is just as prone to overconfidence, extreme predictions, and the planning fallacy”—a tendency to underestimate how long it will take to complete a task—“as it was before I made a study of these issues,” he writes. '

Not to mention that what an average person can or can not do isn't particularly illuminating for non-representative subsets like LW.

In fact it is; there is no substantial difference when it comes to trying to control biases between highly educated and non-educated people.

I am not sure that is possible. Instrumental rationality is just making sure that what you are doing is useful in getting to wherever you want to go. What does "severely overboard" mean in this context?

There is nothing wrong with 'making sure that what you are doing is useful in getting to wherever you want to go'. The problem is the idea of trying to 'fix' your behavior through self-imposed procedures, trial & error, and self-reporting. Experience shows that this often backfires, as I said. It's pretty amazing that "I tried method X, and it seemed to work well, I suggest you try it!" (look at JohnMaxwellIV's comment below for just one example) is taken as constructive information on a site dedicated to rationality.