In our experience with using the guides is that the family readings take 15-20 minutes including narration time. The individual reading selections take about the same amount of time.
Often what we do is we do the family read section and then the kids do their individual reading selection on their own during their school time so they are not reading non stop, we might do family reading then the kids break off and some do math, or another subject on their own Sometimes there is not an individual book scheduled to be read, so it is just the family book to read for the day.
It can also depend on how many children are there to narriate, but sometimes I would just have some of the kids narrate and then the next day I would select the others, but they never knew the plan, so had to pay attention 🙂