We quote one run-time for each script, but this is at best an approximation, since run-time depends on the nature of the production and the slickness of the cast and crew.
To give one example: We estimate that the text-only version of Bill Siviter's "The Scottish Play or Kids in Kilts" has a run-time of 15 minutes. On the other hand, Bill's original school production, with banquets, songs and dances included in the performance, together with extended battle sequences, ran to 90 minutes!
Our estimate is based on the normal rate of spoken English (six minutes of stage time per thousand words). Generally this equates to a reasonably slick production of the text on the page (we also allowa couple of minutes for each song, where appropriate).
Our advice is to look at the scripts and judge whether you can fit them in your available time-slot!