Ankit, For small decisions, it's cultural. I challenge my team in a less structured way than 1-2-3-4-5-6 but still ask how they came to a decision. When the decision goes into another group, we have a nice template for SPINS, and although people push back on the logic (it's designed to encourage that), they never push back on the thought process.

Finally, for large decisions ($Ms), we have a formal assurance process that systematically investigates the decision quality. The time taken to do that is small compared to the value at stake.

Summarising - culture, template, assurance - depends on the decision's scale.