I dunno. I'm not at all certain being paid and shooting trades or TCPs are mutually exclusive. Back when I was operating my commercial studio, I did a lot of model portfolio sessions. Many of them were paid, but some were free. Some of the freebies were arranged by agency bookers to whom I owed favors. But others were done as a means of relaxation and entertainment. I'm a photographer and I enjoy shooting photos. I guess that even as a working pro, I was still an amateur at heart because I enjoyed shooting just for the sake of shooting.
I guess my theory was that if my studio was empty, no paying shoots, then it was empty. I could leave the lights off and watch TV and drink or I could do something for fun, something like photographing a beautiful woman. Besides, shooting a trade portfolio stuff for her and figure stuff for me worked out for everyone. I suppose though, those trades are different from a straight TFP.
Every normal man must be tempted at times to spit on his hands, hoist the black flag, and begin to slit throats.