Great question — answering as the UphillTech team:
In my experience, mostly in North America, an X hour hike provided by a park service is typically given for the round trip unless stated otherwise. You can also confirm by looking at the mileage and elevation. For example, Red Rock provides round-trip hour estimates . For example, Turtlehead Peak takes around 3-5 hours for a round trip; definitely not 6 to 10 hours (at least for an average hiker).
Full answer by ppl: https://outdoors.stackexchange.com/a/4630 (CC BY-SA 3.0).
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