My client had 75 000 service contracts with a revenue stream of 42 different Service Items.
In many cases do the Service Contracts have 12+ Service Contract Lines.

First Problem
The Service Module does not follow standard guidelines for making use of Gen Prod Posting Groups etc.
The only posting group value allocated, sits on the Contract Header called Service Contract Account Group Code, and 100% ignore differentiation of posting from the Service Contract Lines.
The result is all 42 types of Service Items are posted to one GL account in the revenue section of the COA.

Second Problem
The Service Modules totally ignores the ability to allocate Dimension values to the Service Contract Lines, but only take into account the Dimension settings from the Service Contract Header.
This contributes to the problem described above to even make more sure that Service Contract Line data cannot be analysed to at least post a monthly Recurring Journal to clear out the Default value used and reallocate the Dimension Values to where it should be.
The result is all 42 types of Service Items are posted to one GL account in the revenue section of the COA with no ability to correct the dimension values to ensure management can have access to relevant break-out analysis data for their 42 Revenue streams.

This just describes the problems for 1 project. I am facing the same problems on another project I am busy with in parallel to the one above and I have another similar project in the pipeline, which has several more revenue streams.