Caching plugins can be a great asset in serving your WordPress site faster to end-users, but it’s not always a good idea to have caching active. Here are a few website states where using a caching plugin is not a very good idea:
When developing the site
When developing your site you tend to do a lot of changes and you would expect them to reflect on the front-end when you reload the site. If you have active caching then you might not see the current state of the site.
When making changes on the site
If you are making changes to the front end via theme settings or CSS, then you want to have turned off and cleared all caching before making changes, since the site might serve you a cached version otherwise.
When updating themes or plugins
If you are updating a theme or plugins then it’s safer to turn all caching off before doing so. Updates can introduce problem which you might not detect if the site is serving you a cached version.
When you are debugging or having problems on the site
When debugging, you want to exclude everything which might be causing problems on the site. Caching might be one of those things, that is why it’s a good idea to keep your caching plugin deactivated when debugging your site. Read more about general WordPress debugging here.