The difference between operating ten instances and a hundred is not ten times the effort — it is a different discipline. Anything manual that worked at ten becomes the thing that pages you at a hundred.
Deploys must be boring
Every service ships the same way: pull, build, reload, health-check, done. No special cases, no tribal knowledge. A deploy that requires a person to remember a step is a deploy that will eventually fail at the worst time.
Make the fleet observable
Health checks, logs and metrics are not optional add-ons; they are how you know the fleet is fine without looking at it. The goal is that a problem announces itself before a customer does.
Recovery is routine, not heroics
Configuration lives in version control and environment variables, never hardcoded. Any instance can be rebuilt from scratch, so a dead box is an inconvenience, not an incident. Secrets stay out of logs and bundles, by policy and by tooling.
On AWS — EC2, RDS, S3, CloudFront, ALB, WAF, with Nginx and PM2 — this is how Develone keeps 100+ instances healthy in production: not by working harder when things break, but by making them break less and recover faster.