I inject, but I have not catered for over 100 yet. Time becomes a factor.
Also depends on your injector. I have the cajun injector, and it will take a century if I still have it when I do a party of 200 or more.
There are injectors that will work faster than others.
Maybe don't use as much salt/sugar in your injection when cooking outside of competition.
Test, test, test. We BBQer's are much like scientist's. Trial and error.
2 - WSM 18.5, 1 - WSM 22.5, and 1 - ECB Smoke n Pit.