This is a good thing to do if your goal is to gain a deep understanding of something.
If it's just to get it done, I just enforce TDD on my agent and review it's output. I don't need to be an expert in everything (and I am very much a generalist). But if you focus on a very specific thing and only that thing, then yeah what you are doing is a great way to truly understand it. It's slow, but it's totally valid.