Ok, so hours upon hours of restless exploration and only finding slivers of the crap made me more adventurous, and sure enough, my efforts were rewarded. I went to an ice planet (but any risky world will probably work that spawns titanium and not durasteel) and tunneled down to the core. Yup. Massive deposits everywhere, bigger than I'd seen them in any other level of the multiple layers of risky planets I explored. The spawn rate goes through the roof. Just about every time I use my ore scanner and see something silver in the core of a frozen world, it's titanium (risky planet). So it appears the crap is only super rare in the upper levels of the planet, but much more plentiful at the deepest layer. You cannot be near the core. Or bordering the level between the core and whatever is above of it. You wanna be approximately at the middle of the core. It will be worth the effort. I don't need to tell you to bring ore scanners. Happy hunting. Also, feel free to craft a small stack of drains to help you bleed away lava faster in nooks with lots of titanium so you don't need to waste a bunch of time tunneling around.