You have the possibility to create a custom KPI and assign it to pre-configured default Collectors with a Custom KPI. The advantage of the Collectors with a custom KPI is that you don't need to create your own collector in ABAP.
If you decide to create a custom KPI through these type of collectors, you should first choose a collector which is suitable for your goals. After that, you can create a custom KPI as described in the chapter (DI-2105) How to Create a Custom KPI through a Collector with a Custom KPI
Additionally, you can find an (DI-2105) Example: Number of type conflicts when calling a FORM.