I usually dedicate a particular day for putting together the North Slope Insider. I'll search for openings that afternoon and then send the newsletter out that night. Sometimes I run out of time and the North Slope Insider won't get mailed out until the next day. At the most, the gap between searching for jobs and sending out the letter is 48 hours. The majority of the time everything is completed in one day.
I don't have any control over companies that don't remove old postings from their websites. If a job has been listed for a long time and I suspect that the position has been filled, I'll stop including it in the newsletter.
When I search for jobs I use the links off of my Job Resources page. This way I can verify that the links still work and check to see if there have been any changes to the company/employer websites.
I don't use a secret formula to find these openings – everything that I'm doing, you can do too.
Jobs come and go in-between editions of the Insider. Familiarize yourself with the companies and once you have a good idea of the ones most likely to offer the kind of work you're interested in, check their websites at least weekly.