Tryouts involved exhausting re-writes and revisions. After the authors were up all night writing, the cast would rehearse the changes and add them to later performances. Since the 1970's, complex sets and tight budgets make it difficult for most new shows to tour before opening in New York. Many producers now opt for Broadway previews running four to six weeks, charging full price to those adventurous enough to catch a work in progress. Although previews cost less to produce than a pre-Broadway tour, they subject a show to the merciless scrutiny of the New York theatrical community.
Some shows try to extend previews endlessly and avoid the critics.
Merlin cancelled its opening three times, but the critics snuck in and savaged it anyway. Despite the expense, shows still benefit from adjustments made during a pre-Broadway run. Instead of a tour, many shows now start with a full-scale production at a major regional theatre. New shows usually undergo revision during previews. Songs, scenes and bits of business that seemed fabulous during rehearsals are scrapped.