No and yes.
IBO wants your students to come close to earning 150 hours but they don’t want students to focus on earning hours but rather on completing the 8 Learning Outcomes.
This is from page 6 of the New CAS Curriculum that went into effect in 2010:
“This focus on learning outcomes emphasizes that it is the quality of a CAS activity (its contribution to the student’s development) that is of most importance. The guideline for the minimum amount of CAS activity is approximately the equivalent of half a day per school week (three to four hours per week), or approximately 150 hours in total, with a reasonable balance between creativity, action and service. “Hour counting”, however, is not encouraged.”
The way I understand this is that IBO still wants students to earn about 150 hours with an equal balance of hours spread between the categories of Creativity, Action, and Service, but they do not want hour counting to be the goal. This means CAS Coordinators have a lot of leeway when it comes to the number of hours students complete.
The main focus for students (and therefore CAS Coordinators) is completing significant, meaningful activities that will allow students to meet the 8 Learning Outcomes.