The range of time can vary depending on the keyword. Helium 10 updates all of its keyword ranking data at least once a month, but updates some keywords as frequently as daily.
To see when a specific keyword's rank was last checked, hover your cursor of the data. The software will either show that it was updated sometime in the last week, or, if it was checked more than a week ago, sometime in the last month.
To track a keyword's daily rank, use Keyword Tracker. To track a keyword's hourly rank, use the Boost feature in Keyword Tracker.