I've worked for two of the biggest accounting firms, and the generous vacation time is usually compensation for unpaid overtime. So people were offered jobs with two weeks vacation and a pretty-much guaranteed month of 'comp time', because there is really no way to get through a year without putting in 160 hours extra, and usually lots more. There were rumours about a lot of them stopping paid overtime at the entry levels, since they were about the only companies who still did that for professional staff. For IT people there is actually an exemption in the law that says, essentially, that even though you would be eligible for paid overtime in other fields, in computer work, you aren't.