After leaving the sky you should have a minimum of 58 coins. This means you will need to collect the 3 Goomba coins and the 3 coins from the small box. Anything above this leaves you skipping some or all of these. A good amount is 64 coins leaving the sky as this means you can skip all Goombas and the box. If you leave with 66 coins then you can, instead of running around a 4th pole, get the box coins instead. 67/68 coins means you could get a Goomba coin or two to skip a pole and if you manage to get 69 coins out the sky then you can skip everything and only do 3 poles.