My first tries I had the same thought with gyroid and did go up to ~50ish percent, but looking back adding a thicker shell would be something else to try in tandem. The problem I was seeing is that nothing can really support the infill, so lately I was putting some brain cells towards thinking of a way to infuse the piece and fill cavities with some kind of liquid ballast that hardens (kinda like how a resin would) but then would either gradually burn out or that could withstand the heat and use some chemical process to remove.
Spoilers… I didn’t get very far past the idea
Figuring out some way to use less than 100% infill effectively has been a challenge I’d like to solve. I think it would open up the possibility for parts with internal structures and really cost effective prints… but for now solid it is (with the occasional hollow bottom and refractory stuffing)