Thank you kindly for your thoughtful reply, and for sharing your experience.
Wondering if events at other times than those displayed may show up if they are added as events first.
By searching the above user guide for MacOS Sequoia, just found this article:
Change the days and times displayed in Calendar on Mac - Apple Support
Eg: says:
"Calendar has several options for customising how many days and hours are shown. You can customise Week view to show all seven days of the week or just Monday to Friday. You can customise Day and Week views so that the Calendar window shows from 6 to 24 hours of events per day, and you can mark when your day starts and ends.
- Go to the Calendar app
on your Mac. - Choose Calendar > Settings, then click General, then choose options from the pop-up menus.
To choose whether times are shown in 12-hour or 24-hour time format, change Language & Region settings."
If the guidance in the above article is not working for you:
You might want to send feedback to Apple ... if others also have this problem, your feedback helps, and the issue may be addressed in a future update.
web-form for Mac feedback: Feedback - Calendar - Apple
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A few thoughts that may or may not help on using iPad with iOS18 :
Change how you view events in Calendar on iPad - Apple Support
Eg: says:
In the Calendar app, you can view one day, week, month, or year at a time, or view a list of upcoming events.
- Go to the Calendar app
on your iPad. - Do any of the following:
- Zoom in or out: Tap Day, Week, Month, or Year at the top of the screen to zoom in or out on your calendar. In Week or Day view, pinch to zoom in or out.
- View upcoming events: Tap
to view upcoming events as a list.
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At the bottom of this article below:
Keep track of events in Calendar on iPad - Apple Support
Eg: says:
"If you don’t want to use iCloud for your calendar, you can sync your calendar information between your iPad and your computer. See Sync with your computer."
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Also: Search for events in Calendar on iPad - Apple Support
Eg: says:
"Siri: Say something like: “What’s on my calendar for Friday?”
Learn how to use Siri."