They do not last forever. I just picked up two loomis style boxes without the stamp. One was a skunk while the other had one 66. Yesterday, I picked up a box from another bank serviced by loomis, it was a cube box, it gave up 3x40 and 1x90.
I had been getting Loomis boxes for about 2 months with a stamp "APR 17 2012" on it. I was doing 2 boxes a week, and had to take a break from them for a month (my mother got hospitalized in another state so had to stop CRHing). All the date stamped boxes I've gotten have been skunks.
Bummer. I was pretty excited to be getting some Loomis boxes now. This is my first and I am hoping BofA will continue to order them for me. I have a Brinks box today, too. Hopefully there is something in them. I got 6 CWR but the were skunks, old skunks, but still skunks. Alot of uncirculated coins from the 70's and 80's.
Hey Local, I'm here in Michigan too. Most of my boxes are like what you have. It goes in spells but I've done 20 and 60 box skunk streaks.
What part of Michigan are you CRH?