As you go through learning about the CM education philosophy, you will see that most things are taught in short lessons.
When I started out schooling, it was more “classical” and we spent half the day it seems on the subjects because we did lesson per lesson. At one point, my 2nd grader spent 1.5 hours just on a reading assignment. That said, Charlotte Mason is somewhat classical, depending on the definition.
I also have 4 kiddos; because we combine most subjects, we finish in 2- 2.5 hours for everything. Math is what takes the longest because sometimes I have to work one at a time with each kid, sometimes the older girls can do theirs independently. My oldest (15y) added in Highschool Biology, so her day is closer to 3.5 hours.
CM is not as much a method as it is a philosophy- if you look into some other CM groups online, your day may get longer because ages (forms) are separated. I tried and failed at that and returned to Simply Charlotte Mason to bring my family back together again.