What could be a reason to use expert mode in the valuation method for results...

One reason to use expert mode in the valuation method for results analysis is usage of different line ID. Results analysis is a function that allows you to calculate and post values for work in process (WIP), reserves for unrealized costs (RUC), profit from sales order stock (PSOS), and so on. Results analysis uses valuation methods to determine how these values are calculated based on various criteria, such as cost of sales method, percentage of completion method, revenue-based method, and so on. Expert mode is a type of valuation method that allows you to define your own logic and rules for results analysis by using formulas and conditions. One reason to use expert mode in the valuation method for results analysis is usage of different line ID. A line ID is a parameter that identifies a line item in results analysis data. A line ID can have various attributes, such as cost element group, value category, posting indicator, and so on. By using expert mode in the valuation method for results analysis, you can use different line ID for different scenarios or requirements that are not covered by the standard valuation methods. Reference: https://help.sap.com/doc/0f069b2e08b748f1b480d4c8b46c3c49/100/en-US/6a7a9f0a6e421014e10000000a174cb4.html