and/or you have insufficient tooling around your deploys, and cannot separate "deploying code" from "100% visible to all users" with any delicacy or precision.
Unpopular opinion: if your company has a “no deploy Friday” your software quality is too low.
Testing (unit, integration, stress), instrumentation (monitoring, alerting), experimentation (e.g. blind rollouts) should always give enough confidence to roll out at any given time.