If you seek around for scheduling advice, you will see proposals of scheduling yourself working time. Even if you don't seek for advice but happen to be user of the Microsoft platforms, you may find your inbox filled with that advice.
"Maybe you should consider scheduling working time for yourself?"
"You have many meetings in your calendar you have not confirmed"
"You spend N hours a week in meetings and these are the people who appear to be your people"
I have regularly delete these messages, but I have not turned them off. They remind me regularly that you can run your life and your calendar differently.
My calendar is very close to empty. It does not mean that I would not have things to do, I just like being in control of those things more and let my calendar be in control of me less.
A lot of the things people send invites for are information sessions, and I put them in my calendar as non-committal tentative reservations. I generally prefer doing information sessions with 2x speed, and the calendar invites I consider less as meetings in calendar, but reminders of cadence of checking out particular categories of information.
Some things people need me for, and my rule around them is that everything that is supposed to be committed by me, you run by me first. I decide actively what goes into my calendar.
Towards end of a week, I reflect on what I got done and what I want to do next. And I schedule my goals into the invisible slots without putting them in my calendar. This keeps me flexible to saying yes on things that fit my commitments on various level, and makes it easy for people who I really need to share work with find time in my calendar.
But this also means that a great way of upsetting me is to decide you want something done, put it in my calendar and not accepting no for an answer claiming that my calendar is empty.
There is no universal way of how people deal with their scheduling to suit their needs. A safer way is to assume it does not hurt to ping first, ask for consent on scheduling something for a particular timeframe in calendar, and letting people do their own decisions on how "it is only 30 minutes" is sometimes just that, and other times leads into a massive time sink of interrupting type of work that requires attentive time.
My calendar is free so that I can get things done by limiting work in progress.