WElcome to the HE board NEverKnowingly :)
THere are as many different ways of Home Edding as there are families who do it, to be honest. Let me give you two extremes:
Some families get a whole curriculum as a package. Every day they sit down in what even looks like a little school room with desks in their house, and they work their way through today's bit of the curriculum for each bit of the age range that's in the family, with the parent really having the teacherly role, keeping everyone on task, answering questions. Even in such a top-down environment, it's terrifically efficient to teach the material to a small number of children, so it rarely takes more than 2-3 hours to get through the day's work. THose families would almost certainly do "end-of-term" exams within the curriculum package they follow (there are lots of American ones, from ones aimed both at Christian families who prefer a bible-centred education all the way to ones aimed at US diplomat's families (the Sonlight curriculum is a famous one of those)). So for those children, the parents get a clear measure on a regular basis, right through the education, of how the child compares to others of a similar age. Of course, these children sit GCSEs and A levels when they get to the relevant point (although often they do a couple of GCSEs a year when they are ready, from about 12 onwards, rather than doing 9 all in one go).
The other extreme would be families who are what is often called "radical unschoolers". Here there is NO formal learning. The family life basically looks, every day, like one of those long family days in the middle of the summer holidays. They go on all sorts of trips, visit all sorts of fun places (the zoo, museums, petting farms, the library, the park), they have lazy pyjama days, they play imaginative games, they do baking, they play on the computer. The parent divides their time between keeping the house running like everyone does, and answering their children's questions as they arise, and making sure their children have the resources they need to do what they are wanting to do. Months can pass without any sort of formal educational product emerging from that family. THose who live this way believe that their children drink in knowledge through the purposive conversations they have, and through the activities they undertake. THey believe it's educationally best for their children to make the decisions about what to learn and how to learn it. IN these families, there almost always comes a moment when the child has a very clear plan for what they want to do next - and they get the necessary work experience to do it, or they realise that to go to university they'll need a couple of GCSEs (probably maths and english), and some A levels, so they go to college to do those, or they do them privately with tutors, or they do some of the OU foundation level courses, which universities often accept as an alternative to A levels. On this path, sometimes also called "autonomous HE", there are almost always outcomes that everyone recognises as "educational"; the difference is that the person having the education makes the decision about what those things should be.
the first extreme is the one that wider society can accept, kinda, except that of course people often get worried when it's a Christian family and worry about whether the children are being taught to uncritically accept creationism or whatever. [and of course there are easy rebuttals to that if you want me to make them... in brief, that you can't control a child's use of reason for ever, and you can't control a child's exposure to outside ideas for ever and ever, so in the end they get to make their own minds up. It doesn't seem to me to make a huge difference whether the ideology they come to weigh up in the end is the one of their parents or the one of the people who invent the national curriculum ]
the second extreme is the one that wider society finds really repellent, usually. I think this is mostly because it seems like cheating. Most of us spend 13 years in school, and work hard during that time, and undergo boredom and stress and probably times which are socially suboptimal, and we are sometimes sleep deprived because we stayed up last night watching something interesting on TV. And we have to wear clothes that are maybe in colours and styles and materials that we hate and don't suit us. And now comes along Mrs ommmward-smug-home-educating-bastard to tell us that, actually, we could all have got to exactly the same place by being on a 13 year-long summer holiday, going on fun trips and baking with our mothers, and talking about anything and everything with whoever we meet. I mean, WTAF? And then we get into conversations on crazy threads like that one running at the moment which I carefully did not post on before hiding, about how actually children somehow need to learn to be bored and to expend most of their daily energy on someone else's agenda and to get used to spending much of their time in a large group of people, and on an externally determined and rigid timetable, because that will prepare them for adult life. Me, if I am going to have to (let's pretend) have a finger cut off once a year from the age of 22, I really don't see the point of getting in practice for that by cutting a toe off once a year from 4 and a half onwards!
How was that for a long answer? I enjoyed writing it though - sometimes it's fun to present the extremes. Of course, most home edders are somewhere in between the extremes. And of course, most non-home edders are nothing like as violent in their disapprobation as the straw men I set up here - it's all just for rhetorical effect, and I hope it makes it easier for you to imagine the middle ground where most people sit.