Actually, when I think of it, my son's 2008 Cadillac CST had over 250,000 miles on it before it went to the grave yard. It was DGI and it ran fine without any servicing of the DI or valve cleaning.
I have 140K miles on my 2016 DI Tahoe. No DI servicing or valve cleaning. Plus I am in tons of traffic on the B.Q.E. in NYC often.
A few police agencies in Broward County are running 2015+Tahoe's. Spoke to a few Leos and they said no servicing of the DI system. They have tons of idle time on them as they prefer their vehicles ice cold when they get in them in South Florida.