Because of this intentionally variable structure , duration may vary considerably from one version to another .
Stagings to date have been between three and three - and - a-half hours ( Ehman 2013 , 51 , 179 ; Loskill 1982 ) .
Because of this intentionally variable structure , duration may vary considerably from one version to another , but stagings to date have been between three and three - and - a-half hours ( Ehman 2013 , 51 , 179 ; Loskill 1982 ) .