It is largely a situational matter. If the brood nest is choked with syrup and you add a super it's more likely to end up in the super because the bees want more space to raise brood.
The "need" to feed is largely situational too, along with being a matter of personal preference. Personally, the only reason I ever see a "need" to feed is to prevent starvation. I really like the fact that the bees are good at collecting their own food, and I like to encourage them to do so.
A number of people have asked if they "should" be feeding, but not all have indicated if they are dealing with a package on foundation, a package on drawn comb, or an established hive. I'm glad to hear you say that you don't feed established hives in the spring--I think that's useful for new beekeepers to hear. If the boxes are all full of drawn comb and the bees have access to honey or nectar they really don't need to be fed. Some think it stimulates brood rearing; I think they are plenty stimulated enough to rear brood by instinct, the season, and the pollen coming in.
I started my packages on drawn comb and gave each a frame or two of honey and pollen. I haven't fed them at all as I didn't really see a point in it. All of the capped honey has been moved out of the initial frames they started in and into cells around the edge of the brood nest. They've also brought in pollen this week and packed it mostly into cells in a ring around the patches of brood. Brood in the center, a ring of pollen around the brood, and honey/nectar around the edges of the frame. It's quite fascinating to see how the bees naturally organize their resources and to watch how this changes as a new hive grows. You miss seeing some of this when you're feeding them heavily because they're sticking the syrup wherever they can find room. You also risk triggering them to swarm early when they're filling the brood nest with syrup.
I'm not trying to vilify feeding. There's just a lot more to the equation than "should I be feeding or not". I think it's important for people to understand why they should feed or why they don't need to feed, and that feeding can cause unintended consequences too. The "why" part of the feeding picture doesn't always come through clearly.
Joe