At our CAs in Dudley, UK, we were expected to remain seated and reserve clapping until the end. Which we all respectfully did.
A couple of years after leaving, I accompanied my still JW wife to my last ever CA and I was shocked by the behaviour of some of the brothers/sisters. Instead of the usual respectful silence there was a general hubub of chatting and walking around.
The brother who gave the baptism talk had to come out MID-BAPTISM and announce (tell us off!) how serious the baptism was and to please respect the occasion by remaing quiet and seated.
Such a shocking change of attitude in just a few short years.