You have defined your parameters so that resource bottle necks will not arise. Your applications make RFC calls of the permitted types only. Yet you have realized that more work processes than allowed are occupied with RFC calls.
This can happen in the following circumstances:
The asynchronous RFC transmits one or more synchronous RFC calls in the destination system. For these the profile parameters are only valid if rdisp/rfc_check is set to 3 in the target system.
In the Work Process Overview of an instance (transaction SM50), you can see that many dialog work processes are occupied with the program SAPLARFC. You might also see update or batch processes with the status stopped RFC.
This is because in transaction SMQS as many tRFCs were started at the same time as the parameter settings allow and this has resulted in the user contexts losing their rollability. This situation arises for instance when mass data is processed. See SAP note 726148 for more information and possible solutions.