That's great (though I'd quibble about a few of them, eg I was doing input validation in Excel 25 years ago, and boy do I feel old now), but while you're learning to do all that great stuff you're not learning anything about the domain you want to work in.

OK, I don't know who wants to work in health insurance but the basic point is Excel is a good tool for people who have specialist knowledge in a particular domain and want to automate their work. Programmers know the best way of programming but frequently overestimate their understanding of other people's problems.