Assigning Wip Accounting Class to Cost Group in Standard Costing Org with Project Mfg

Hello.

We are on 12.2.3

Is there any benefit in assiging wip accounting classes(WIP module) to cost groups in a standard costing org using project mfg ?As per the documentation this is required if you have different item costs by cost groups but in a standard costing org can you have different item costs by cost group or projects even if you have project mfg?

Thanks

Rahul