I used to never say no because I couldn't stomach letting Isabelle down (HER FACE WHEN YOU REFUSE) but after a while I just started saying no to all of them, especially when cycling.
I say no most of the time. In my first town I made sure to get every single ceremony picture.. But with my 2nd town I can't be bothered. A lot of them are temporary so I'll probably start going to ceremonies when I build the actual PWP I wanted there.
Yeah, I've said no a bunch of times. I usually don't have time/feel like going to the ceremony. I like to go into my office, get what I need done, and leave.
I always say yes out of habit. I don't think I've ever said no to Isabelle. XD Plus, it also slightly increases the chances of a villager pinging you right after the ceremony. It avoids the trouble of trying to find them. My villagers tend to disappear into the museum or shops so it's handy. =v=
I say no about half the time. I don't always feel like it, especially with small PWPs, so I try to do it with the bigger ones like bridges, the lighthouse, etc.
I'm a heartless mayor... I always say "no" to the ceremony haha it's because I TT a lot, because I'm trying to get all my dream villagers and cycle out the ones I don't want, and the ceremony always takes so long, especially just for some lamp posts LOL
I say no more than saying yes... lol I just don't care much about 'em, and don't always wanna bother having to walk back to city hall afterwards. the other day, I went to get my campsite built and forgot the last thing added was the roost, so I said no because I don't really care, even though I know Brewster shows up too. :x