Moderation in meditation for lay people Vipassana-style meditation has been adapted to treat patients to prevent recurrence of depression and anxiety through MBCT, and to treat chronic pain and stress through MBSR. More info on this can found in this answer.

On the other hand, there have been some reported cases (see here) of people who attended the 10-day Goenka vipassana retreats and became psychotic and suicidal.

I have also heard that such negative effects may be a normal part of a meditator's progress, called the "dark night" or "death of the ego" (according to this answer). These could be part of the sixteen stages of insight (according to this page), namely bhaya nana or "knowledge of the appearance as terror" and adinava nana or "knowledge of the contemplation of disadvantages".

Questions:


Are episodes of psychosis resulting from 10-day vipassana retreats the result of something not right (e.g. pre-existing mental conditions, the side effect of combining other techniques such as mantra or tantra with vipassana), or is it a normal part of progress in vipassana meditation? If the two are different, then what is the difference?
For lay people, are the Goenka retreats considered too intense and thus out-of-moderation? Is it better for lay people to attend weekly sessions and spend less than an hour daily in meditation, rather than the intense and rigorous Goenka retreats?
Is it better for lay people to practise in such a way that they will not reach the "dark night" stages because these stages are more suited for monks?
Is it required for lay people to find a teacher who can determine what is moderate for them, or can they just follow generic instructions?
Daniel Ingram writes a lot about the 'dark night' and working through it. In an interview (Buddhist Geeks I think - sorry no exact reference) he said that dark night will be encountered by


Intense meditators who really go for it - many hours a day over months
Committed but steady meditators who meditate every day for around 30 minutes and maybe go on a week's retreat once a year. Then after 20 years - bang - they are in the dark night


So according to Daniel you don't need to be a intensive meditator to get the dark night effects. You just need to be reasonable committed and practise over a long enough period. So advising lay people to moderate probably wouldn't be effective - at some point they are going to hit something unpleasant. Perhaps the best thing would be to make them aware and give them tools to cope. That approach is one of the major themes in Daniel Ingram;s book.

On a personal note - My practice is firmly in the second category but I have banged up again some crappy stuff. Not "dark night" but crippling doubt and inability to move forward for extended periods. I think it just happens.