Hehe, sorry that's not explained but I didn't want to make it too difficult so you can play levels at your own pace, get the coins first and learn the layout then go for zero deaths then fast time or whichever order you want :)
As I said, I may do a master mode in an update which would switch the levels to need you to complete all stars in one go, but that needs some deep testing to make sure everything is possible with the current par times. Plus I would need to think of a reward for doing all the levels in master mode.