Hi Hugh,
In my experience it’s been critical to learn not just InDesign, but the other major Adobe programs as well (Illustrator, Photoshop and Acrobat). Because I learned those four programs, when the opportunity of a lifetime presented itself to me, I was ready. I wrote an article awhile back about my experiences. https://documentgeek.blogspot.com/2013/02/why-you-should-consider-becoming-adobe.html
That article speaks at length to the Adobe Certified Expert program. Personally, I think the ACE program quickly becoming irrelevant (due to poorly written and very expensive tests). But regardless, the preparation required for such tests proved invaluable. You see, I am self employed. But prior to that, when I was working for an employer, I lost my job 5 times because the companies kept going out of business! I never had a job more than 2 years (The typical tenure was much shorter). since becoming self employed with my own specialty publishing company, I have had the same stable job for nearly eight years!
Keep studying and learning!
.
