Researching another post I came across this little gem from September 9. The article suggests that posts to Facebook via third party apps can reduce their reach by up to 88%. Originally data from the use of Hootsuite and Tweetdeck were used as examples, but the data was later withdrawn. There’s been no follow up to explain why.
If you use a third party App, you might like to run a little experiment or two of your own to check the efficacy of your campaigns.