Note:

The timeout clock for queries and sessions only starts ticking when the query or session is idle. For queries, this means the query has results ready but is waiting for a client to fetch the data. A query can run for an arbitrary time without triggering a timeout, because the query is computing results rather than sitting idle waiting for the results to be fetched. The timeout period is intended to prevent unclosed queries from consuming resources and taking up slots in the admission count of running queries, potentially preventing other queries from starting.

For sessions, this means that no query has been submitted for some period of time.