They are probably still investigating the cause of the problem, they could have maintenance every day for 5 hours to "increase the stability of the instance servers" until they find the root of the problem.

They will be running simulations on their test environment to locate the root cause of the issue, if they don't find the root of the problem it will reoccur. Remember they changed the core of the instance system. They made huge changes and these could not have been tested under real time server load (you can simulate it but not on a live system with hundreds of thousands of connections).

Just because there is not daily maintenance doesn't mean they aren't investigating the issue.