Another important thing to consider is the clothing worn during
rehearsals. So the actors may get a feel for what their final
costumes will feel like when they are performing, it is common
practice for them to wear similar articles of clothing during
rehearsals. This lies mostly outside of the realm of responsibility
of the costume designer. However, it is the costume designer's
responsibility to let the director and cast know what they will be
wearing so they can wear something appropriate to rehearsals.