Are you running more than one type of course, or courses catered to different audiences?
If so, you can create multiple schools if you need to - you'd simply need to sign up for a second Thinkific site at www.thinkific.com!
It's worth noting that our plans are per site, so if you're considering upgrading your plan in the future, you would need to have a plan for each.
Alternatively, you could run multiple types of courses on the same site and simply divide them up into categories - it really depends on how separate they need to be; e.g. would the courses need separate branding (colours, logo, etc)? If they do, then having separate sites may be your best option.
If you would like to discuss this further, then please feel free to get in touch!
Just to clarify, if I have multiple sites, can I still manage my courses CENTRALLY or do I have to replicate each course and each change for each site separately?
Since all your sites are actually separate accounts, you would have to manage them separately. To make it a bit easier, you could use the bulk importer so that you can load all your files at once to the second site you create.
Hope this helps!