A lot of skill and time is required to get a star rating of 90 on all trials. There are 32 time trials (including the Pure Time Trials) for you to obtain up to a 3-Star Rating in each.
The maximum star rating is 96, so there is little room for error.
Some tips for beating the target times:
- Don't always use the most obvious routes, There will be various other routes that can shave many seconds off your time.
- Take advantage of the ability to download the ghosts from the leaderboards.
- Try to plan out your route before you attempt to break the target. It helps if you plan where to jump, when to jump, etc.
- If you get lost at any point during the new trials just look around for coloured blocks (usually red, purple, pink, yellow). These are the slowest, but easiest routes to follow.
Check THIS thread for videos that may be helpful for the Time Trials.