We could just have easily said " Put the ***.BGL files into your addon scenery/scenery folder" it would achieve the same result, BUT!
It is better practice to use the Addon Scenery folder as a tidy place to keep other folders i.e.
Within my addon scenery folder I have a RTMM folder with a scenery subfolder, into this go all my RTMM ADEX.BGL and ADEX.CVX files that are not intended for other places (such as the Traffic.bgl, ALT.bgl files, they live in the FSX/scenery/world/scenery folder)
I have a separate folder for the actual scenery files, these are the named files such as khutzeymateen_river_01.bgl
This folder is my IS folder (Instant Scenery) and of course it too has a scenery subfolder
In this manner I can keep track of all the RTMM sceneries and easily locate them should there be a problem.
I do the same thing for the EZscenery files and several other scenery areas are managed in the same manner.
I always then add any new folder to the scenery library to activate it.