Yes, the 3-2-1 method is also called the Texas crutch and, from what I've read, is used in competition to achieve desired results quicker. However, my experience has been the same as several posting here who have stated that the ribs got over-cooked after 2 hours in the foil. One of my smokers is a Traeger and I've found that I can get away with just spritzing with apple juice (and sometimes with a half Jack Daniels mixture) and cooking low and slow. So, I've stopped using it when I use the Traeger. However, when I use the wood/charcoal smoker (side fire box), I find that I might need to foil for about 20-30 minutes after 3 hours of smoking to keep the spares juicer but still get them cooked within 4-5 hours (longer and they really get dry on me in the wood smoker). The foil method actually steams the meat and raises the temp quickly. This can cause the fat in the meat to melt too quickly and exit the meat prematurely. So, I really limit the foil time when I use it at all. When I'm using the wood/charcoal smoker, better to smoke over a water pan, spritz, and monitor closely than to foil in my opinion. I use the foil as kind of a fix in case the ribs are taking too long and I'm worried about them drying out. Hope that helps a little.
Randy