The challenge with natural check-ins is everything else in our world is scheduled and it will eat all time not allocated. I block off the time and the schedule tells my team mate "This time is for you".
I trust my teamm members too, but it's not their job to proactively bring up every problem in a timely manner:
Some people/cultures will not do this but they will respond to empathetic, well thought out lines of questioning.
some problems are very sensitive and scary and don't need the added burden of "going to the boss to ask for some time to talk"
Some problems are not apparent and the 1-1 gives you a forum to discover them
Some very serious problems are not viewed as problems by your team members. A huge part of a manager's job is to identify them early.
I do a lot of the casual and emerging management stuff as well; 1-1s are not mutually exclusive. There are bad 1-1s too: right now with everyone remote I think the quality has gone down because we can't capitalize on the personal aspects. You learn that the 1-1 process is the easy part; actually giving a shit and working at building relationships is the hard part.
I've been in bad 1:1s and good 1:1s, there's definitely and art and skill to executing effectively, and the playbook you use can potentially be different for each team member.
A natural check-in every once in a while is much preferred in my book, I trust my team members to bring up actual problems as soon as they see them. A leading question forcing some reflection is fine but forced meetings for the sake of the meeting is wrong.