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Technically the signal always also travels between, but it's not a concern until roughly 50 MHz and above. It's actually the rise time that matters, and how long the signal takes to rise relative to the trace length and propagation speed.

This is probably a good video for understanding - https://www.youtube.com/watch?v=icRzEZF3eZo

Basically, go watch every Rick Hartley video on YouTube. He is awesome at explaining. It will become intuitive instead of being a bunch of cargo cult advice. (Normally I dislike long videos but this is absolutely worth your time if you design PCBs.)

https://youtu.be/QG0Apol-oj0

ADD: in short, it happens for "any" frequency. This is how a voltage signal propagates. However, for DC it happens once because you see "change" in voltage only once and that's it. As you increase the frequency, you'll end up seeing more voltage waves due to "change" in voltage. That's when "reflections" come into picture - happens due to discontinuity in impedance.

Between 0 Hz and infinite Hz.