[choeger]

Note that "canary deployment" (I hate the usage of 'deploy' as noun.) is only possible under specific circumstances. You would not want to do that with your database, for instance (aka, "0.5% of your data might now be corrupt or lost) or your development tooling (aka, 0.5% of your deployed code might not do what it should do according to its source code).

[plopz]

You also need a large enough user base/level of traffic where releasing to a small percentage of your users would even uncover a problem.

I've had similar problems with A/B testing where a low amount of traffic means I would have to wait a long time to get meaningful data during which confounding variables naturally get introduced.