Is There A Best Case Scenario Which Minimises Carbon Build Up In EGR Circuit?

Just wondering what is the best driving style to minimise carbon build up in the EGR circuit?

Sustained Freeway/Highway driving vs City stop and start?

Higher octane gasoline (petrol) (91-92 (95 RON in Europe or Australia)) or (94 (98 RON in Europe or Australia)) or an Ethanol blend?

Anything else?

I’m in Australia and my 2011 Gen 3 has 106,000 miles (170,000 kms). I’ve been trying to find a mechanic to to take the EGR cooler pipe to see if there’s a build up but they don’t want know about it given the work to get at it. I have done mostly highway/freeway kilometres and always use 91-92 or 94 gasoline. The fuel lid specifies 95 (91-92) minimum and that it is ethanol compatible ( which i’ve never used).