The need for further responses depends on the situation and your audience.

• When someone emails about moving the time of a meeting, they need confirmation that you received and read the email. 
• Cultural differences might inform when you stop responding.
• Power differences. The CEO may end the email circle quickly, while the clerk may take longer.

If you're included in an email thread with many other recipients, you don't need to reply to everyone. You can only respond to the sender unless the group needs to know your response. It is reasonable to have a sidebar conversation with only those who need to be included.