For the changi Wifi, the data is unlimited. Will they throttle down the speed when hit certain limit?
It would take a lot to hit the daily limit for Changi WiFi. I had 3 devices connected to one, quite frequent transfers of photos (via WhatsApp), upload photos to FB now and then etc. By the end of the day my mom was even using it to watch YouTube on her mobile and it still didn't hit the limit.
However there was once (a couple of years back), i connected my laptop to Changi WiFi to do some work in the hotel. While waiting for my work emails to load, I absentmindedly opened chrome on laptop and loaded YouTube to play some songs in the background. The WiFi got throttled almost immediately and I had to switch to hotel WiFi...
So bottom line, on mobile you won't use too much data no matter what you do (unless you are torrenting 24/7). So you won't really hit the cap for Changi WiFi if you are using only mobiles. If you are looking to connect your laptop to it, then you'll need to be mindful of the websites that you are loading.