Just now , I was at Punggol and I only saw a maximum of 24 mins
but actually quite good already.
Which means the 24 mins train is at around Dhoby Ghaut and from
Punggol can see how long to reach PGL already.
If you can, try to get on to Buangkok or Hougang during 5:30 ~
6am and notice the Punggol bound train. You will be amazed. Things
might have changed since.