My advice is to keep your aid climbing and your free climbing separate.
Strictly speaking, this is good advice. However, when I took up aid climbing, it changed my free climbing perspective significantly. Seeing how my placements worked under load exposed much of my unfounded fear during free climbing. Placements that I previously believed were "dicey" were shown to be bomber. My appreciation and trust of a good nut placement, for example, which I really learned
during aid climbing, has enabled me to truly *free* climb through situations where I was previously bound by fear. It is no longer a question of whether the placement will hold. It is all about whether I
can hold on. In other words, aid climbing has educated me on what the actual boundaries of safety are, reducing the grey zone and expanding my view of what I
am capable of.
In reply to:
For me at least, aid climbing upped my free climbing abilities by at least one full grade.
For this reason, I believe that aid is a fast track for improving one's trad free climbing ability, and so I recommend it to everyone.