At my workplace which deals with millions of customers. What we have is essentially a segmented clone of prod. It's a 1:1 copy of prod with real data flowing th

At my workplace which deals with millions of customers. What we have is essentially a segmented clone of prod. It's a 1:1 copy of prod with real data flowing through. We use feature flags to enable-disable features. This way when our devs ship code to prod - it first lands in this segmented clone. Then incrementally changes are propagated from this segmented area into actual prod-prod.