Honestly I found it a blessed relief. I struggle with the middle bit, I feel like I don't suit the role of it and neither of us like it.
When they're little they really need you for everything and that's obvious and they are happy to accept that as the norm as well. So that's easy in terms of knowing where I stand. And they are very cute when they are fully dependent and you can fix everything easily which is also nice.
When they are 18+ they are adults and can make their own decisions and you can't tell them what to do any more, you can offer your own experience but it's ultimately their choice. This role starts to come in from about the mid teens and I enjoyed that a lot. When I could stop trying to cajole DS1 to eat and just say this is what we're having for dinner, but if you don't want it there's bread and pasta and whatever you want in the cupboard. When I could stop fighting him over homework and just say you know what, you do it or you don't, your teacher is going to be angry at you not me.
In between IME there's a lot of conflict because as the adult you know best and they don't but they want more autonomy than they really can handle. I don't like that! I don't like making people do things they don't want to do. I am not especially comfortable in that role. Children also don't like having someone tell them what to do even if they are ultimately happier with rules and structure than without it.
I won't lie and say the teen years have been plain sailing - he's 17 and currently battling school refusal (unfortunately we are abroad so he has to stay at school until 18) but although this is stressful because it seems a shame for him to throw away the easiest chance he'll ever get for this qualification, I am not worried about it. I think he will be ultimately fine. He doesn't seem depressed or burnt out. If he doesn't finish school he will find something else to do - if he had his own way he would alternate casual work and travelling, in fact I expect he will do exactly that once he turns 18. And that's no bad thing to do. I think he will be fine long term and I'm curious to see what he ends up doing. I find my younger two - 4 and 7 - more stressful in a way, because there is a lot of day to day cajoling and chivvying.
And yes it probably did help a bit that the year he turned 13 I had a newborn and a 3yo to relive the gorgeousness of the tiny days, so I don't feel like I'm losing him because I'm still in the thick of parenting a family.
But I hope it won't feel like losing him even when he does leave home, TBH. Or when the younger two get older.