Google announced yesterday that they have upgraded the Google Assistant to hold a conversation with you in a more natural way with "Continued Conversation." Continued Conversation basically does what it sounds like, you can be talking to it and not have to say "Okay Google" to trigger yet another question and answer response.
So you can start it off by saying "Okay Google" or "Hey Google" and ask it repeated questions without having to say "Hey Google" before each question. Google wrote:
With Continued Conversation turned on, after you ask the Assistant a question, you can ask a follow-up, set a reminder, or add something to your shopping list without having to say “Hey Google” each time. You can say “thank you” or “stop” once you’re done, or we’ll end the conversation once we detect that you’re no longer talking to the Assistant. You’ll still need to activate your Assistant devices with “Ok Google,” “Hey Google,” or with a physical trigger, but with this new optional setting turned on, the Assistant will stay active for long enough to respond to follow up questions so you don't have to say “Hey Google” as often.
This needs to be turned on, it is not on by default and you can turn it on by going to the Google Assistant app by going to Settings, then Preferences, then Continued Conversation and switching the toggle on.
This is now available on Google Home, Google Home Mini and Google Home Max.
Forum discussion at Twitter.