Making Sure Everyone Is Ready

Beyond staging rehearsals and technical preparations, a large number of further rehearsals take place during the course of filming. Sometimes they only cover one workspace. For example, a stunt rehearsal when the sequence of a stunt with or without an actor is worked out. In a scene with artificial rainfall, SFX rain is tried out and judged by the camera. With the help of an extra rehearsal, the assistant director gains an impression of his or her background staging before the actors arrive on set. Costume and make-up samples can also take place during the shooting process if they were not completed in the preparation phase. The need for all these rehearsals is determined by the requirements of the shoot.

https://en.wikipedia.org/wiki/Rehearsal
https://en.wikipedia.org/wiki/Technical_rehearsal
https://nofilmschool.com/2011/02/tdc-rehearsal
https://www.raindance.org/rehearsing-actors-dos-and-donts/
https://www.nyfa.edu/film-school-blog/the-5-stages-of-blocking-a-scene/
http://howtofilmschool.com/block-light-rehearse-tweak-shoot/