Semestered vs Year-Long Learning

I'm still thinking of my son's grade 10 (first year of high school here) year next year and how things will be organized. Even though I don't have resources picked out and more important things that need to be decided at this point, but it's on my mind. Although, the scheduling is part of figuring out how we'll actually go about things, what kind of time we'll have and what we'll be able to do with that time.

Technically, a semestered course should have just as many hours in it as a year-long course. So that's not really the kind of "time" I mean. It's more: How many hours per week are we going to have on a subject? How long are the individual sessions going to be? Then there's, Do I provide structure in terms of what we do on which day? Or do we just have our things to do for the week, the time is blocked out to pick those things? Or a mix: certain things, like reading and writing workshop time, are scheduled (or put on a certain day) and the rest just has a certain amount to work through?

The advantages to doing semestered is that you can be done with that course and move onto the next thing. The disadvantage is that you kind of have to plow through it and don't necessarily get to really absorb it. And if you don't have to kind of student who is prepared to plow through things...

I was originally thinking of doing some things semestered and some things all year, like perhaps social studies and science semestered and the rest all year. But now I'm second-guessing that. Is my son truly prepared to spend 5-7 hours a week on social studies for 4 months? It's doubtful. lol. It's just really not his style. And part of homeschooling him is to make this high school experience fit well with him, to approach things in an enjoyable way so that learning--even topics we wouldn't have chosen--is enjoyable. I'm also thinking retention. Now, I know the one online math teacher here recommends that students do the math course in a single semester because by the time the final exam rolls around, they've forgotten too much of the beginning stuff, but shouldn't that just mean that better review needs to be built in during the year so that it truly is retained? Yes, that's what I'm thinking.

What about you and your family? What do you do for your high school students? Do you use semesters or have you done it both ways and prefer one over another?