Cleaning turbo do or don't?

Years ago, this question came up. Please do some searches on YF.
The low / air side does take some abuse from crank case vents (Walker, Racor).
It may be just a thin oil film but any thing can slow a turbine down a micro amount and MAY cause reduced turbo boost.
The larger concern is the condition of the inter-cooler that you can't see. This is where all mfg's have issues and recommended service / replacement intervals.
Just think of that oil film, dust, salt, other blown onto the thin walls of your inter-cooler.
Look in there if you can also.

Then, exhaust silt on the exhaust side could really turn your stomach. Virgin and clean fuel at load usually burns this off.

Of course, this does not apply to my Detroits;

Have you noted any reduction in performance?
If not, don't do anything but follow the mgf maintenance schedule.
Please re-read #3 above.
It's usually the inter coolers that take the first restrictions. You did not spec your engine model.
Later engines will offer boost or pressure data at a few points. These have hopefully been tracked in your records.

Although there are water based products out there, I am very leery of a DIYr spraying water into an engine device at any time.
There are folks out there who have done this and the engine survived. No results reported if any performance was found and no blown motor results reported either.

My last advise; Never kick a sleeping dog..