For T. zebrina, it will grow in any light. Your preference of leaf color would be the only rule to go by. Mostly shade - green leaves with white/gray stripes, bigger leaves. Medium light = pretty purple stripes appear. Tons of direct sun = red leaves, that are smaller.
T. pallida grows in full sun outside here, a hardy perennial, though all day sun isn't necessary for it to look great. The only rule I know with this one is to just give it enough light so it doesn't lose its' purple color.
When I snap a piece of T. pallida and put it in a pot, the original piece almost always dies off, but new growth should appear from the roots. Hopefully that's what yours is doing!
While plants are inside for winter, they might look funky, etiolated, pale, but that's fine for Trads. They will bounce back quickly outside again next summer. My plants suffer since I have others that take precedence over the great-light spots. I don't consider either of these stand-alone plants though many do have them that way. They are much more interesting to me and easier to keep looking nice as filler in pots with other plants. I've developed this weird aversion to being able to see the soil at the surface of my pots, so don't take this last part as advice if you don't like the idea, just me babbling stuff I like to do.
