Simple answer: “You should.”
Probably will raise some hackles.
The first reply should been to have a knowledgeable experienced roofing professional to go with you to evaluate the roof that you do not know what to look for. Most anything else would be fraudulent. Obtaining an overnight “Certification” of some kind sounds good (marketing) but really doesn’t cut it either.
Knowing, understanding and having experience of the past 70 years of shake materials and installation methods is crucial. Knowing how installation recommendation/methods have changed and why those have failed and why is crucial. Getting a few tips does not ethically cut it if a professional inspection and evaluation is to be performed.
5" exposure and labeling was mentioned and that is just the tip of the iceberg. 18" or 24" double sawm, hand split single sawn, treated or untreated along with #1 Blue or Black is in the beginning. But that is far from a true start for acceptable understanding.
There is also the aspect of being able to determine the difference between a roof that has a bad appearance and one that is functionally bad. Shakes have the ability to look bad but are just fine. Knowing the difference is experience and knowledge and to often the uninformed the mistake is easily made.