With so much note taking apps nowadays, I can't understand why does anyone still write notes with pen and paper. You need to bring the notepad, book or that paper to retrieve that information, and most of the time you don't have it in hand. While my phone almost always reachable and you carry when you go out. For those still like to do handwriting, there's many app does that and they can even convert it to text notes.
So, if you still write notes with pen and paper, why?
I have an A6 pocket notebook that I carry around in my pocket and I keep notes in there.
Mostly I just map out the next few weeks at a glance and then note down things I have to do day by day. Sometimes I make an extra entry to take notes on and plan things in more detail as needed, e.g. my upcoming holiday, the itinerary, my flights and visas and accommodation and transport and a few things to do in each place, or the wifi password of a place I'm staying, or notes and thoughts on something I'm researching.
My notebook never distracts me the way my phone might, and it's easier to keep my notes accessible over the term of a few weeks, because they're just there.
I still use an online calendar and obsidian for more long-term notes.
Edit: I also sometimes use my notebook, which cost about 0.50 €, to stabilise a wonky table. I wouldn't do that with my phone.