Well only certain ones, and for specific purposes. I generally leave it off (it connects and disconnects in 2 seconds with the little flip lever).

For sighting in, or for accuracy at longer distances, it helps tremendously. I can easily hold groups at and beyond 50 yards with this attached. Without it and hands only hold, 25 is pretty much the accuracy limit. Although I can still hold it on the paper at 50 yards without much problem, the groups will open up at least 3-5x.