Sometimes the functionality of the current r_keeper_7 version is not enough, for example, it does not support a certain type of printer. Then you can test the opportunities offered by the new version, upgraded to support certain functionality, for example, it has a new driver for a printer.
A new version usually gets tested after the entire system has been upgraded. In some cases, you might need to test just one app from the package or even just one module (for example, the dll file) for compatibility.
If only one module is being replaced in RK7 you should switch off the parameter correlation control module and switch off the cash register upgrade (launch the cash register without preload.exe).