I always piss certified mechanics off when I say this, but ASE certificatons are a joke and always have been.
One thing I will say for it though is that at least it demostrates the willingness of a technician to attempt to better themselves.
When I was in the heavy truck and equipment industry, the company I worked for gave finantial insentives to the techs if they got ASE certificatons.
I chose not to and instead went for as many OEM ceritifications as I could. Every one of them was a week or more of training and testing, and I learned something at every one of them. I had several certifications from Cummins. Mack and Kenworth, Eaton, and several other. But never bothered with any ASE tests.
Several others at our shop went for ASE because it was easy and got them a little more per hour.
I am not saying that those techs were not good. Some were very good, others not so much, but they all were exactly the same grade of technician before and after ASE testing. The only difference was a framed piece of paper hanging on the wall.
I have said from the early days Before it was called ASE, that it was more of a sales tool for the shop than it was a certificaton of the shops employees.