AV integrators get asked to shorten commissioning on almost every project. AV is nearly always the last trade to finish.
The painting runs late and pushes the carpet. The carpet pushes the furniture, the network comes up late, and the AV depends on all of it. The end date does not move, so the lost days come out of commissioning. A system planned for a month of commissioning gets 3 days.
When I ran projects I had a habit. Every time the schedule slipped, I said the same sentence in the meeting. The schedule has pushed 2 days, and our end date has pushed an equal number of days. It did not always work, though sometimes it helped an owner see that longer hours and more people were not going to buy the time back. More engineers do help when a building has 40 identical rooms. They do not help on an integrated system, where each step waits on the one before it. Commissioning takes time, experience, and attention to detail, and tired engineers on a short schedule miss things.
On a large corporate project in Houston, we were held to a completion date that was reasonable when the project started and unreasonable by the end. The owner had a business need for the rooms on that date, so we turned them over unfinished. Then we came back at night to do work that never belonged on a punch list. The system we eventually handed over worked well and exceeded what the customer expected. It took longer to get there than it would have with the commissioning time we planned.
We made the date, and the project finished later because of it.