I sit next to a DBA and it can be really feast or famine for him. If there are patches to install or a failure of some sort he may work a 12 hour day. Other times he is just monitoring systems and reviewing performance reports, maybe 4 hours work. If he is involved with a development effort, then it is more engaging work and more of an 8 hour day.
We have a DBA but with an augmented job description. They write ad hoc reports which some will be passed to the development team to be codified with filters and export options.
I remember DBAs with just database experience in the '90s and they were really busy especially when drive storage and RAM was very expensive.
But today, both are cheap and databases are easier to configure and support, I suppose their job descriptions are more expanded.