I would guess that they have some calculated cost per guest's entertainment... Or maybe they simply add up the total number of potential seats in rides and seats in shows and then divide it by the total number of guests to come up with some event per guest number and if they can cram in one more show by making them all a few minutes shorter it would increase the total number of rides or events by the size of the auditorium... So I could probably see some bean counter claiming that they increase total guest experience by .2 by shortening the show time... kind of reminds me of the last time I was in line at the Dumbo ride at DL, I timed the rides and they were under 1 minute in length... I just can't imagine that they were that short when I was going there in the 70's... But hey someone probably figured you take a 2.5 minute ride and make it a minute you've increased the guest experiences by more than 100%.
As one of those so-called bean counters who did budgeting for over 20 years, shaving off 2-3 minutes of shows like Pirates Tutorial, Jedi Academy isn't going to save hardly any of those beans. Biggest recurring expenditure is salaries - not just what is paid directly to the employees, but all the employer paid benefits and taxes. If you have a show every hour at the bottom of the hour, in a park open from 9am to 10pm - 13 hours - that's 13 shows per day. Shaving off say 2 minutes per show isn't going to provide time savings in salaries because CMs are paid by the hour for a typical 8 hour shift, not by how many shows they perform in, bathrooms they clean, ears they sell, etc. And the other costs associated with putting on a show - costumes and props - will not change if a show is shortened by 2 minutes. The only way costs would decline is if Disney looked at a per unit cost basis. And took the 26 minutes reclaimed and added an additional show or two with shows every 45 minutes or so. But that might mean increasing the number of CMs in a particular shift to cover the additional shows (there are wage & hour rules governing breaks/meals during a typical 8 hour shift). Which will drive up personnel costs. Thus negating the so-called cost savings of shortening a show 2-3 minutes.