In a real time SAP Consulting we will get most of issues related to the performance bottlenecks in day to day ABAP reports, BW Data loads, hanging work process and critical business KPI's needs the SAP System to run more optimized way.
An ABAP consultant or BW consultant know their solution well, but when it comes to finding the root cause of any performance issue like in BW data load, it needs much expertise to understand the SAP system as a whole, so you need to have a very good tool to help you for that diagnosis.
SAP tool ST12 comes into help for that. You can use this tool to identify what is happening in the SAP system when a ABAP report runs for a long time or what is happening in BW system when data load hangs. You will find the root cause of the performance issues, then you can solve that to avoid that performance bottleneck.
You can become expert in finding root cause of performance issues the SAP Solution's, It can be an ABAP Report, BW Data load or general SAP System. You will have leading edge over other fellow consultants if you know how to find the root cause of performance bottlenecks. Grow you SAP Career more better with the expertise in this SAP tool.