SRL is very effective at Splash Mountain. I am always by myself when I go to DL, and all you have to do at Splash is get a Single Rider pass and head to the exit and go up that way. Have literally ridden this ride 10 times in one day this way, and during pretty busy crowd times.
Have also used it at Soarin' and Grizzly River Run. As mentioned, not quite as effective here, but it still beats waiting in a 60 minute + line!