The way I see it if it is in free stuff section or in the free stuff forum, then it is there to be used by everyone if you give the creator of the free item some credit then I see it as a no brainer (if the picture is going into a commercial product like a comic then that may be different and finding out what the creators stance on commercial use certainly helps).  

The main thing though is that it gives the creator of the free item a sense of "Wow so cool to see someone use my creation in one of their renders."

But in all it is up to the creator of the picture, for me I use a lot of free items where I can but most of my pictures use purchased content.  

You know you enjoy 3D Art when you realize that your life is a piece of 3D Art. :)

AMD 7900X3D, 64 GB Corsair Vengeance DDR5 Ram, Asus Prime X670-P Wifi MB, PNY RTX 4070Ti Super 16GB, 14TB SSD's & HDD, Windows 11, Poser 9 / Pro 2012 / Pro 2014, Daz Studio 4.22.