Homeowners - foundation settlement risk

How big of a risk is this for homes on sloped lots - especially in the valleys or homes built on the ridges?

Is it just a matter of time until some shifting occurs or can you assume with proper construction and reinforcement it would be low risk?

We are considering a home built on a steep slope. Everything checks out but the sloping lot gives me a little worry. Just trying to go in as informed as possible - any thoughts or experien would be appreciated. Mahalo!