The adhesive on the back of the LED strips is some odd stuff. It is extremely tacky. Makes you think it will stick to anything. In my case, I stuck the strips to cleaned, flat, coil coated steel ceiling angle. 
That surface should be ideal for a press-in-place adhesive. And sure enough, when I first put the LED strips in place the adhesive grabbed aggressively. As soon as it touched something it stuck. There was zero indication the application wasn’t going to work. After all, it was labeled 3M and that company has a stellar reputation for making quality stuff.
Three days later…. I open the train room door to find several LED strips either totally laying on the floor or at least seriously drooping. This was the last thing I expected. At first I thought perhaps I had not pressed it down well enough during the installation. Painstakingly I reinstalled all of the fallen strips making sure to firmly press every inch as I went. Confident the problem was solved I went about other tasks.
Three days later…. See a pattern here? Three days seems to be an important time span for this adhesive. What to do, what to do?
Off to the local dollar store to buy every package of clothes pins they have. 11 fifty count packages to be exact. With the most flagrant offender of LED strips back in place, a clothes pin 
was placed on every LED. All 300 of them plus 250 of the next strip’s LEDs. Then I waited. If three days time is so critical then the pins need to stay on at least that long. I left them on for a week from Saturday to Saturday.
The above adventure began over a month ago. Truth be told the issue started even before I had the lighting system finished. I took the clothes pins off temporarily when I had the LEDs turned on and to take photos. At that time I didn’t know if the solution would work or not. Who knew? Maybe it wouldn’t make any difference how long the adhesive was clamped. Maybe it only sticks for three days regardless of the application.
I am pleased to report the adhesive that has been pinned for a week seems to be stuck extremely well. The first strips that were pinned have now been unpinned for over three weeks and show no signs of letting go as before. Even if I tug on a LED the strip doesn’t let go. Big sigh of relief. The solution is working.
550 LEDs at a time I am working my way around the layout. Pin, wait a week, move pins to next 550 LEDs. As of this writing I have one more segment of LEDs to pin starting next Saturday. Fortunately, the 
slight detour from plan doesn’t impede other activities.
So, if you are relying on the LED strip adhesive to hold your strips in place then find some means of clamping them for a period of time after installation. I would have expected more from a 3M product. 🙁
I would expect the adhesive to work better than it did. It’s not like it haas to hold much weight. I hope they hold. Thanks for keeping is updated.
Greg Amer
The Industrial Lead