My input on this topic is this:
I see on my 2015 regens every 230 - 300 miles, depending I guess on how much highway driving I do. The last regen was closer to 225 miles because my wife drove it for a few weeks with rarely any highway trips, only short trips to school and back with the kids, etc. My commute adds some highway time, maybe 15 minutes or so but doing that consistently yields the regens at closer to 300 mile intervals.
I use a Bluetooth dongle that connects to the car's OBDII port, and the $5 torque pro app on my phone to monitor the EGTs. I can tell when a regen is happening and usually I will keep driving until the temps start coming down from the >1000 F range. I wait until it is below 450 to turn it off, or below 400 if I can really wait a few minutes longer idling in the parking space, or the driveway before entering the garage. Some people use the ScanGauge, or other items out there that are a bit more expensive but maybe easier to use, less use of the phone while driving, etc, or for the wife to be more in touch with the car as was mentioned before. My wife is of the mind where she does not think of these things nor pay attention to it.
Volkswagen's stance on regens seems to be: if you turn off the car and the fans are running, it was likely in the middle of the cycle, and the regen will just resume when the car next drives and reaches 38 mph. I agree with
When driving on the highway it is not easy to tell that the regen is happening. If you accelerate hard, the car may pull a bit harder due to the increased amount of fuel being injected, and of course the MPG numbers will drop a bit. And of course if you are at a stop light, and the car's idle is around 1000, it is likely doing the regen, although there have been times that she is idling that high and the torque app readout indicates that the EGTs are normal level. I sometimes will get a slight diesel smell through the air vents but not always.
As far as the coking goes, I am interested in this topic too. Does that occur if you shut the motor off during the cycle when these components are at these high temps, not being allowed to cool down with oil circulation or exhaust flow? That makes sense, I used to own a 2.0T Jetta some years back and I learned that it is good to idle the car for 30 sec to a minute before shutting off the motor, to allow the turbo to properly cool down first so coking does not occur, especially after driving with lots of turbo use. I think some GTI people have talked about that on GTI forums.
Some of those gasser turbos had turbo failures and a few VW techs (one of them has over 20 y. experience) have attributed that to this coking thing by around 80k miles. But of course, that always varies.
I think a the TDI turbos are more often consistently engaged than the gasser ones because they spin up at lower RPMs so I believe it is a good thing to let it cool down before turning of the motor.
Sorry if that was too long and straying from the topic but I wanted to give the newbie some info.
Cheers.