Conditions for turbo boost fail

^{Disclamer: I have yet to find an answer from and official or reputable source, and I will update the answer once a more authoritative voice has spoken.}

Short answer: No.

I haven't seen it at all in any of my playing of the game, and according to a few topics such as this, it was done to offset the fact that he now rescues you much faster, often putting you a little ahead of where you originally fell off.

There are 2 levels of boost. If you are driving a kart, you can tell which one you get by how many of your exhausts spit fire. If both spit fire, then you've got the maximum boost. If you are driving a bike, then your bike will do a wheelie when you get the maximum boost.

If you watch the numbers come on the screen it goes 3 - 2 - 1. The numbers kind of drop in from the top. You need to hit the button just as the number 2 gets to the bottom of it's downwards animation. It takes a bit of practice but after a while it becomes second nature.

Another tip is to count it down in your head - then you get the timing just right naturally!