You may already know this, but I found out by accident out of creating some convenience for my wife. I started a 7.5 lb turkey breast before I went back to work from lunch. I told my wife all she had to do was dump the chip loader after about 30 mins or when the smoke thinned out. Well it didn't thin out for about 1 hr and 15 mins or so. She pulled the loader to see if the chip tray was what was burning. She said the chips in the loader are what had kept it going because they were ash.
I basically double loaded the smoker with chips by first loading the chip loader then dumping it. Then I reloaded the chip loader with chips again and did not dump them. It worked out that the chips in the chip tray burned first. When it was finished the chips in the loader burned. It made the smoke last about 2-3 times longer than if is just loaded the chip loader and dumped. I have since tested it a couple of times and it works great.
I hope this makes sense.