Quickly check the last note to remember what I was doing? Often. Search through? Rarely, maybe once a month. The times I do though it's really helpful. I realized I was forgetting lots of semi important things that had no default place to write down.
This frequency informed the design, in fact. Easy to write, easy to read the last couple entries, moderate difficulty in finding older entries (in exchange for lower cost of making individual notes).
I think for me this is why it's so important for the system to be almost zero effort, else I'll just kinda stop using it. Just having an ubiquitous default place to dump something out of my brain helps.
Of note. A very slightly modified version of this runs on an ancient Thinkpad in my bedroom for diary/mental health reasons. I find the separation helpful. Those I almost never ever read, but I think that's the point of those.
Edit: at work I didn't really use this system, it's mostly for my own life. At work I used the ticket tracker, wikis, and calendar. I found that taking personal notes at work was best substituted by making actual documents that my team could find and use. There were much fewer uncategorized tasks at work.