You work hard for your money.
So you want to be a Water Damage Restoration Contractor? The first step is knowing how to deal with water, since that is the cause of the problems you are going to deal with, right? Unlike other professional tradesman that have a licensing board to which you must show you have mastered the science and protocols of the trade, you have stepped into swamp of half-truths, mis-truths and outright junk science to become certified by your industry. Nevertheless, you are going to spend plenty of time and money getting your IICRC certifications. Is it a waste of time and money? Yes it is if your goal is to provide the best service to your clients.
How can this be you might ask that the boards that certify me in this trade don't know what they are teaching is junk science? The answer is greed. A shame for you and your clients but it is greed all the same. The industry is dominated be dehumidifier manufacturers and they made up a science that sells dehumidifiers. Good for them not so good for you and your clients. The instructors, many of whom know the science they are teaching is junk, dare not go against the manufacturers if they want to keep their jobs.
Sadly, there is little you can do about this since the IICRC controls the industry and they are dancing to the dehumidifier manufacturers tune. What I recommend is that you keep the financial outlay to the IICRC to a minimum and learn the true science of water, it's properties, and how to evaporate water. Once you have done that invest in equipment that will actually evaporate water since that is the only way you can get the building dry.
Google "water evaporation" and learn the science of water evaporation. No industry in the world would follow the guidelines of the IICRC, and the fact is none do. The question is why not one industry on earth would use the methods you need to learn to become certified?The answer is does not work, it does not dry, and is just childish thinking. If your goal is to provide the best service for your clients, you must educate yourself.