Unfortunately, even after years of testing, they still have not satisfactorily solve these issues. And to make things worse, even the newer train stations that should not suffer from wear and tear, are facing some sort of problems. In view of this, the SMRT have also recently announced that they were doing system checks on their North-South and East-West lines, which are the oldest MRT lines in Singapore. SMRT have also announced that carrying out the checks during the June holidays is the best to maximise their ability to aggressively run tests.
Now the latest news coming out from SMRT is that all-day performance checks of the new signalling system on the North-South Line are necessary to "work out teething issues". What this means is that SMRT is telling us be prepared to face delays from trains at any time of the day. They don't know when it will happen, but it will happen. Much like that other tagline, "Not if, but when". Same with the MRT system, not if disruptions will occur, but when. So be prepared.