I spent just over a year in Cosmo School, (1600 Hours in CA) I went roughly 40 hours a week or so, sometimes more, but thats because I didn't have a regular job and was able to complete the course faster, Most schools require a Minimum amount of hours a week, I think mine was somewhere between 25-30 hours a week.
If its what you REALLY POSITIVELY want to do, Than do it! It is kind of pricey, but if its what you want, do it.
I graduated, went to State Board and got my license ( I passed state board the first time around, If I can do it, ANYONE can do it.. Im a terrible nervous wreck when it comes to that stuff ) I didn't go on to doing anything in the beauty industry though, Its just not something I can do in California, I am far too sensitive and the women here mean SERIOUS business with their hair, and if its not right they WILL yell and scream at you. (made me cry on several occasions lol !) Its not something I can handle in my every day life.. So I went another direction, but I still keep my license Current , Just in case ( and also to get awesome deals on professional shampoos and haircare products lol)