Billing & Invoicing Ousorting

HI Experts,

Please let me know process steps how the Bill amount standard validation done in ISU Billing module.

Is the Ousorting check groups for Billing process is created for each Rate category (of single Billing class) or created at Billing class level. which one is the SAP best practice.

Similarly for Ousorting check groups for Invoicing process, is this created at Billing class level?

For example if there are 100 Rate category created in system and it is possible that customers within the Rate category 1 will definitely deffer from customesr of Rate category 2, the difference will in terms of prices,consumption pattern and demand.

So now in above case, can i create different Outsorting check for these 2 Rate categories? Please confiirm and guide.

Thanks in advance.