To add to this, there are specific baton patterns for specific time signatures. For example, a 3/4 time signature motion looks like the baton is tracing a sail on a boat since it has 3 corners - up, down/across, horizontal back to the start position (anyone correct me, it’s been a long time).

A musician following the conductor has a clear visual timer to verify against plus he knows which beat of the measure they’re on.