The correct order to carry out the payroll process is as follows:
Start payroll. The system calls up a country-specific payroll program and performs payroll using the values you entered in the payroll program1.
Check result. You check whether payroll has run correctly, or determine where errors have occurred. If desired, you can obtain a detailed payroll log1.
Exit payroll. You exit the payroll run and set the payroll area to "exit". This locks the payroll area for the current payroll period and prevents any changes to the payroll-relevant data1. References = 1: The Payroll Process | SAP Help Portal

In SAP HCM Payroll for SAP S/4HANA, wage type selection rules are built using several elements. These elements are grouped into a rule group, forming different regulations for the selection of time wage types1. Each individual rule within a rule group contains the wage type to be selected1. The selection of a wage type is determined by whether the conditions specified in an individual rule are fulfilled1. Two of these elements are the Processing type and Conditions for the day1. References = 1
https://help.sap.com/docs/SAP_S4HANA_ON-PREMISE/85346b7b83c8474e993429d934f77cc0/de38c2531bb9

The retroactive accounting depth of SAP payroll is the earliest date from which the payroll results can be recalculated due to changes in master or time data.
The retroactive accounting depth is determined by the following settings:
The "Earliest personal retroactive accounting date" stored in the Payroll Status infotype (0003) for the personnel number. This is the most specific setting that applies to an individual employee. It can be changed manually in the infotype or automatically by the system when certain changes are made.
The "Earliest retroactive accounting period" in the Payroll control record. This is the common setting that applies to all employees assigned to a payroll area. It can be changed in the payroll control record or by using the report RPUCTD00.
The hiring date stored for the personnel number. This is the absolute limit that cannot be exceeded by the other settings. The payroll results cannot be recalculated before the employee's hiring date.
The system uses the latest of these three settings as the retroactive accounting depth for each personnel number. For example, if the personal retroactive accounting date is 01.01.2024, the payroll control record date is 01.02.2024, and the hiring date is 01.03.2024, then the retroactive accounting depth is
01.03.2024. References =
Retroactive Accounting | SAP Help Portal
Retroactive Accounting functionality in HCM payroll PART-I | SAP Community Retroactive Payroll Processing | SAP Help Portal

Executable Schemas:Executable schemas are designed to be run directly on employee data during the payroll process. They contain the complete set of rules and functions necessary to execute all aspects of payroll calculations. X000 is a standard international executable schema provided by SAP.
Non-executable/Subschemas:Other schemas like XPPF, X010, and XT00 serve as components or building blocks within an executable schema. They might contain functions or calculations, but they cannot be run directly on their own.

In SAP HCM Payroll for SAP S/4HANA, wage type fields rate and number can be multiplied in a calculation rule using the MULTI ARN operation. The result of this operation will be stored in the amount field. To set the values in the rate and number fields to zero after the multiplication, the operations ZERO=N and ZERO=A are used1. References =
https://answers.sap.com/questions/9074890/wage-type-for-multiplying-a-rate-with-amount-and-d.html