Split tunneling is designed ONLY for sites connected to the internet, but do not have any other way to get back to the corporate network. It is not for Campus locations that otherwise have a route back to corporate via site to site VPN or regular routing.
In a regular network, where there majority of client traffic is to centralized resources away from the site such as email, web servers, file servers, etc., you would have a tunneled SSID. Traffic between sites and the corporate network would typically be fast. There would be minimal traffic that needs to stay local for things like printing.
In the use case where there are significant local resources, and the majority of traffic destination is at that site (email on site, file servers on site, web servers on site, etc.) it is advised to just have Aruba Instant, where traffic would be bridged locally.
If you could, I would engage an Aruba partner to design the network properly so that you get the right fit for your environment early on.