When implementing a SDLC program, is anyone using risk approach to allow the software to go ahead on the different stages or is it a more black and white approach?

Of course! Having a risk methodology that you can implement from early stages of development is essential.

They key success factor is manging the risk through the SDLC life cycle.

SDLC's are risk based almost by definition, you ask for only N code reviews, you rely on test automation which is limited by nature, and you accept the risk in importing third party libraries.
To answer your question, it really depends on your context- in a highly regulated environment with you would lean towards the black and white, while in a high paced consumer product startup you can make risk-based assessments.

We use a risk-based approach for some of the tasks in the SDLC especially for the ones that can't be cleanly automated or where there are additional costs. This requires that you have a risk assessment process that can be applied to the solutions moving through the pipeline. You have to have confidence in the risk assessment, and it has to truly differentiate between those items that need additional controls and those that can move on.

You should build these indicators or attributes in such a way that they can be used by your pipeline process to make the decision to move forward.