For those investing for young children, how do you think about balancing 529s vs. taxable accounts?

My 2-year-old recently received a five-figure inheritance. He already has both a 529 and a UTMA, and I’m evaluating the tradeoffs between the different account types rather than looking for a specific recommendation.
My initial thought was something like:

\- 80% into his 529
\- 10% into his UTMA
\- 10% into a separate brokerage account invested in a broad-market fund such as an S&P 500 or total-market index fund

The reasoning is that college is likely to be the single largest expense we’ll face on his behalf, but I also don’t want to overfund a 529 if there are compelling reasons to maintain flexibility outside of education.

For those who’ve managed investments for children, how do you think about the tradeoffs between:
\- maximizing tax-advantaged growth in a 529,
\- maintaining flexibility with a taxable brokerage,
\-and using a UTMA despite the loss of parental control at the age of majority?

I’m especially interested in the *why* behind your allocation decisions, any tax or financial-aid considerations, and anything you wish you’d known before setting up your children’s investments.