This is a very good topic, something that also weighs on my mind heavily.
We have an Indian Ringneck, his name is Zoltin, and he is still very young, I am not hugely experienced, but have learned so much about these birds over time.
Our work hours are very long, and often unpredictable, I can never say what time I will be home on a day to day basis. both my wife and I start work at 4:30AM, which is great for Zoltin, because I can assure that his night time cover is taken off before we go to work, that way Zoltin receives natural sunrise. My wife works close to home, and drops in to check on Zoltin every morning, at around 9-10Am. After that we could be home anytime from 1:30pm to 5Pm, (either one of us will be home between those hrs anyway). Unfortunately we never know what time we will finish until that day. Irrespective of that Zoltin will always have an absolute minimum of 3hrs out of cage time with us on a daily basis. Generally much more. He is out of cage with us from midday every weekend. Baring in mind that life has its obligations! And weekends can be taken up, in which case we allow Zoltin the maximum out of cage time with us as possible. (It actually gets ridicules! We have to leave events or tell family or friends that we really have to go so we can get home for our bird!!! Most don't get it!) Zoltin's bed time is around 8:30pm, currently we are in daylight savings time, so the sun begins to set around this time, his cage is in our lounge room, so lounge room lights go off, and Zoltin gets natural sunset. When its dark Zoltin's cover goes on his cage so he is in dark, we generally have no need to turn the lounge room lights on after this, but if we must we can. (TV is always on during this time, which generally gives us all the light we need, and we usually need to get to bed fairly early). So far everything seems to be working well, but we have a long way to go yet! We need to watch Zoltin over time vary carefully, and if needed the consideration of another bird as a companion for him may actually be a necessity rather than a choice. And I will tell you why. My son is 16, so he is home now due to school holidays, he has his own flat downstairs. So we know that when we are not at home, Zoltin wont shut up! He screams a lot, which worries me, because he is bored and feeling lonely, irrespective of the toys he has in his cage. On the weekends we try to get a sleep in, Zoltin wakes early, and is very noisy until we get up, then he will be more quiet and settled, because he has company. Although Zoltin's routine is not perfect, he is very forgiving, but if we stray too far from routine, that's when we will get bitten, that's when Zoltin becomes the household terrorist. (In those times my wife has nicknamed him isis! I just tell her that isis is actually a beautiful Egyptian Goddess, so thanks for his compliment!!!). Otherwise Zoltin is a very very good bird.
Aside from a very basic run down of our life with an IRN, a very big point that I want to make is that a bird, (any bird) will ultimately effect every part of your life, in fact they will even run your life to an extent. Meaning everything we do in our lives your bird must be seriously considered. So that is what we need to be prepared for if we choose to accept a bird into our lives, if you don't think you can do that, no matter how much you want a bird, don't get one!
Now for what I have learned about an IRN in particular. I have never owned another species of bird, so I can only speak of my personnel experience living with an IRN, I've had 2 so far.
The IRN are pure silly fun! They will make you laugh till you have tears running from your eyes! They are amazing acrobats, and they will show you trick after trick. Their intelligence will blow your mind, they are extremely quick to pick up on training and lessons. Their little brains seem to run a hundred miles an hour. They will be involved in something intensely until the next minute they will be involved in the next thing, and this goes on! But in contrast if they have their minds set on something then God help you! You had better figure out a distraction or a solution otherwise watch out! Yes they can be very individual, they can play and be very comfortable on their own, however they also need as much of your attention as possible to enable them to be comfortable on their own, if that makes any sense, otherwise they can very quickly revert to a wild state, which would concern me if your IRN spent many hours by itself, along with the calls of its own kind from the wild. We have many wild parrots and birds where we live, and Zoltin does react to their presence. And will try to interact with them, I certainly wouldn't want to lapse in my attention to Zoltin on a daily basis, otherwise I believe we would be in trouble. I must say that I don't think the IRN is the easiest bird to deal with, I think they are very head strong, and require a lot of time, understanding and patience.
I know this has been long. And there is much more I could say as well! But I hope I have shed a little light from my personal experience with the IRN.