Q: Your SLO is 99.9% availability. Your current availability for the month is 99.95%. A development team wants to push a massive refactor on Friday evening that hasn't been tested thoroughly. What do you do?

SRE uses Error Budgets to make data-driven decisions between feature velocity and reliability, removing the emotion from the conversation. With a 99.9% SLO, we are allowed a 0.1% error budget for the month. Since we are at 99.95%, we have positive error budget remaining. Technically, they have the budget to deploy. However, Friday evening deployments violate the core risk mitigation practice of having support available during business hours. I would advise them: "You have the error budget, but deploying Friday night risks a major outage over the weekend. Because an outage will burn through the remaining budget—halting all feature deployments next week if we drop below 99.9%—I strongly recommend waiting until Monday morning when the team can monitor the rollout safely."