Sadly, the "long hours" culture appears to be endemic amonst private industry as well - most companies in The City expect their employees to put in similar hours with the expectation that you "live to work, not work to live".
There are a few companies that are starting to realise that these long hours do not benefit the business in the ling run duw to staff stress, illness, tiredness and morale and are trying to change the culture.
This may filter down to the Forces in time since the "long hours" ethic seemed to have reached there later!
Cheers
Whirls