Would you do a change request if specific risk didn't occur and therefore, you didn't need the related contingency reserve?

I would file for a change request only if a large amount of resources (financial, human, etc.) were earmarked/allocated to respond to that specific risk and only when I was absolutely certain that this was a phase-specific risk which won't be carried forward into the next one. If that isn't the case, it wouldn't be prudent to ask for contingency reserves to be withdrawn.

I'll need a bit more elaboration on the second part of your question.

Soha -

I think we need to separate theory from practical application.

A good practice is to tie contingency reserves to specific milestones along the life of your projects so as those milestones are achieved, any unused contingency reserves would be returned to funding bodies.

I have also seen cases where contingency reserves are held in the project till the very end even if the identified risks which had been used to quantify/justify those reserves have expired. While this is not "by the book", decision makers also don't like to be hit with administrative change requests. The risk in doing this, of course, is that these reserves get abused for funding scope changes. It also represents an opportunity cost at the portfolio level to unnecessarily tie up funds.

Kiron

Project costs monitoring and control has to be performed along the project. While it depends on each project governance process defined into the organization the money for project risks that have not been materialized is debited from the project budged. Because of that, project risks must be correctly defined mainly the related dates. Then, no change request is needed.

Sergio,

That's interesting, thank you.
It would be great if we attain that level of maturity :)

Soha,

I agree that decision makers generally don't like to deal with small project deviations. In the scenario you described I would create a table showing the risks that didn’t occur and the contingency funds I could return to the funding center. I’d then post the table somewhere and inform the decision makers about it, explaining that I’ll keep the funds within my project to cover unknown unknowns unless they request them back, and that I would update the table throughout the project. This gives the decision makers the option to reabsorb the funds at any time while avoiding the hassle of processing many change requests. In my experience most decision makers have no problem leaving the unused contingency funds attached to the project until its conclusion.