Let's be honest TSW needs more AI, if any of you play TS Classic you'll know you may see more trains in 5 minutes than in 2 hours in TSW this is especially clear on Rapid Transit.
The problem is, that there isn't that much rolling stock out yet that could do that job, let's take RT as an example: While the City-Tunnel should actually have more services, there aren't that many services in outer sections of the line like at Dessau. While the RE services could be done with the 182 and the Dostos, even if a bit unrealistic, ICE or IC services can't be done because there aren't any such trains available right now. Also, you can't serve these trains because Leipzig Hbf and some sections of track where these trains would run aren't fully modeled. I also don't think DTG is going to update RT anytime soon.