I personally have it set up in a model so it rebalances periodically when it gets out of balance. Just a simple equal allocation of those stocks. I mainly do it this way because I find it easier to teach them about it when it's the individual companies they can see in the world around them.
www.holisticplanning.com/intro
Remarkably personal financial advice for a fuller life.
We have/had UGMAs and 529s for each of our kids. We retained ownership for the 529s though.
Both my wife and my mother-in-law were investment advisors. My MIL had the idea of letting the kids pick stocks when they were young. It was interesting to revisit them earlier this year and see what picks were good and which were bad.
Regardless, they will have some seed money when they get out of college. Nothing huge, but soemthing.