Risk is different from Equipment to equipment.I can share my experience about risk for liquid based products.
For instance you are cleaning a tank with impeller:
-Area to be cleaned
-Area to be cleaned that is not covered by product inside the tank
-Inside the impller wings
-On the shaft
-Bottom or base of impeller
-Contact time of detergent
-Recovery od detergent after the rinse or swab analysis od various points from Base drive impeller or propeller impleller.
-If you have propeller impleeler how the crevices in between the bolts analaysed.
-How much of detergent or product left over?
-What is the overall cross contamination ratio in the next product of different API or same API?
-Did these accumilated minor amounts degraded in solution by bacteria and formed toxic compounds?
-What is the cross reactivity with detergents?
Can you improve the design of tank or impeller so that the cleaning will be better?
How o you clean valves and joints?
How is recovery done from a valve that is placed at the bottom of the tank?
Are there any dead legs if the tank has a recirculatory system?
Many possible questions will be arrived based on experience and knowledge of Subject Matter experts(SME’s).
We always prefer to have Engg, QA,QC, Production guys to be a part of this particualr risk strategy.