In the world of trading short selling can be very misunderstood.
Here’s a page on short trading stocks and CFDs that is recently put up onto the website that explains it.
There are a few things to note here.First is that some traders use short trading as a stand alone system.
Some people prefer shorting and have a well tuned system to a particular index or stock or forex that they really know.
Second, is that many traders trade multiple systems both short and long at the same time.
There are various permutations.
It could be long trend following, and short trend following.
It could be long trend following and mean reversion shorting system.
It could be long trend following, and short trend following, mean reversion long and mean reversion short system.
The idea of combining systems is not new. but depends on the quality of the system.