Why are you worried or even considering a service to remove carbon build up?
Just a guess re: cost of service, but given the amount of time to remove the intake and do the cleaning: ~$500
I like a clean and leak free engine as much as anyone. But once you start disassembling the engine expect to find oil inside the intake - a fact for every engine design since PCV valves sent excess crankcase vapor back into the intake (30+ years or more?).
But what is "bad" carbon build up? That should be defined by impact on engine performance.
So - I've got to disagree with several of the posts here - including the excellent YouTube video: The amount of carbon build up that is shown is not enough to cause performance issues.
Was there a problem before the cleaning? Maybe I missed that part of the story - but it seems like people have pulled the intake and are aghast with the oil and carbon build up they see. But, based on what I saw in the video, there is lack of experience that would provide a reference for comparison. A review of the YouTube video: The oil in the intake manifold and in the runners in the cylinder head leading to the intake valves is completely normal. 100 miles after re-assembly it will look the same and have 0 impact on performance. The amount of carbon on top of the valves, also was not enough to restrict airflow and was still soft enough to be easily removed with a toothbrush and solvent.
Hopefully everyone is educated enough about direct gas injection to know that the gas and oil have no impact on the amount of carbon that builds up on the top of the intake valves.
Adding an oil catch can system will theoretically have some impact by removing some of the oil in the crankcase vapors that are recycled into the intake. But, there is no way to prove an oil catch can is necessary or even to quantify how long you will delay valve cleaning. And, a bit of irony is that the compulsion that leads to installing a catch can is likely to result in that same owner pulling the intake and cleaning the tops of the valves as part of preventative maintenance.