where PMBOK Guide helps us

So, you have a schedule with 100,000 activities, including lots of details. Will you succeed in managing your project? Not necessarily. In fact, chances are high you won’t! I’ve been in such projects, and we always tried to fix the problems by adding even more details to the schedule. It never worked. 
What’s the problem?

The problem is that scheduling is only part of project management, and it won’t be effective if you don’t cover other domains. Project management is like a chain, and each domain a link. The chain is only as strong as its weakest link.

That’s where the PMBOK Guide helps us. It helps us understand the chain and make it stronger. For example, it doesn’t tell you how to measure progress; instead, it tells you how to connect that measurement to other aspects, to make it effective

انجمن مهندسی و مدیریت ساخت ایران (ICEMA) Iran Construction Engineering Management Association