7 seconds?! It is so much power to handle for the server. It continues php file that will use a little cpu power to work. When you call it every 7 seconds. It’ll launch it so quick times that will reach your cpu limit. Which can Suspend your account
You can change it to every minutes instead of 7 seconds.
The exact timing is up to you to decide. But please do realize that every time your script polls the data, it will generate a new hit, create a new entry process, and consume CPU power and memory. If you keep this page open for a long time, or many people use it, you can easily blast through your resource allocation.
Whether 7 seconds is good or not depends on your website and your traffic.