I would never put my faith into a single Wait Time App. Most rely on user provided data and are only as good as the last time someone in the parks entered information. When a lot of people are entering times, they tend to do okay. When it's a slow day, the wait times can be really off.
Regarding Touring Plans specifically, they say they use a statistical method for predicating wait times that produces wonky results to me. For example, they predict that at 5:00 pm on July 4th (as in the major holiday), the wait time for both Indy Jones and Space will be about 45 minutes. RSR will be about 75 minutes. I kind of think these are all under-predictions.
When I use the wait time apps, I tend to look more than one (e.g.,
Disneyland Wait Times, MouseWaits, etc.) to see if there is any consensus.