Vision score should rank like this: Support > Jgl > Rest. Support should always have the highest, because they are the ones with warding item. Jungler should be the second, because of the vision orbs in the jungle. You should always be warding, the enemy jungle especially. This is especially important if you can't gank till lv6, because you'll need to track the enemy jungler and provide information for your teammates about the enemy. But it can vary. If you are playing against a good Kindred, then it's crucial to know where they are. If you don't, then you won't be able to deny the stacks from her, and believe me a fed Kindred is unstoppable. Most junglers neglect warding because they rarely encounter champions like Ivern or Kindred, these two can only be stopped if you ward properly.