Consolidate your events into one calendar
Reading this Macworld article by Lex Friedman on how pro Mac users handle their calendars left me thinking... Am I managing my own calendars well? I took a few tips hoping to tweak my own but that only helped me to discover what a mess my solution was: Using Fantastical and iCal simultaneously, I simply add events and reminders on the iPhone as I need them, but how are they being saved and synchronised? I don't remember when I stopped my Google Calendar and I don't understand why I have multiple iCloud calendars called Home, Work and even a random one simply called 'Calendar'. Some work needs to be done.
The first step is to consolidate all these calendars into one. This is the approach that works for Joe Kissell and Shawn Blanc, according to the article, so I'm going to try to merge all the stuff into one. I'll only add a second calendar if I really need it for sharing appointments. After some Google searches, it looks like the best approach is going to be to export all the information on my calendars as a backup and then build "The One" calendar from scratch. Accidentally deleting any entry could be fatal, so I want to make sure I'm keeping all the events safe somehow before tinkering with the calendars.
If you're using the built-in iCloud calendar sync, the only way I've found to backup this information is on the web interface, as described by randers4 on this Apple Discussion 'How do I export iCloud calendar to Google calendar?'. We are only going to use part of the steps here and forget about the bit importing them to Google's platform — what we will do is to consolidate them into one calendar once we have saved everything and cleared the multiple Home and Work calendars to keep only one Calendar across devices.
Backing up your existing calendars
To backup your iCloud you need to log on to iCloud.com/calendar → Select a calendar → Click on the stream icon on the right → Make it a public calendar. Now, notice the long URL text on the description of the calendar you just made publicly available. You need to copy and paste on another browser tab. Replace the first word webcal bit for http and hit enter. Two things will happen automatically: a file will start downloading and the Mac Calendar app will automatically launch to import it (decline this for now).
If you look in your Downloads folder you will find a randomly named ICS file (red and white icon), which is a copy of all the calendar events you just made public on iCloud. To backup other iCloud calendars simply repeat the same process from iCloud's web interface until you have all the ICS files downloaded on a safe place.
The second stage for this calendar spring-cleaning is to delete all the calendars associated to your calendaring apps. Since you are on a desktop right now, the quickest option is to do this from the standard Calendar (formerly iCal) app. On the default view you have a 'Calendar List' pane that you can enable or disable on View → Show Calendar List. See those calendars on multiple colours listed under the iCloud label? Right click on them and delete them one at a time. You have all the information backed up already, so you know it's fine to get rid of them. If you launch any third-party app that uses iCloud's calendaring function, you will see how these are deleted there too as soon as the changes are pushed to the server.
Merge and consolidate
The most exciting stage is to retrieve those ICS files you downloaded before and start adding them one at a time. Simply double-click on the first one and add them to your new "One Calendar" that will contain all the events you had spread on multiple calendars before. The result can be a bit rough around the edges depending on how messy your situation was before. If you see duplicate events it's because you had multiple events initially.
Once you have imported all the content, I recommend changing name and assigning a new colour (right click → Get Info) and see the changes take place across applications. This is completely optional but it will reassure you everything is going smoothly. Go through your recurring events and amend anything as necessary.
Some things to look out for:
Birthdays appear automatically on a separate calendar with the information pulled from your Address Book.
You can subscribe to public calendars, like bank holidays, and label them with a different colour.
You can upgrade this setup with a shared calendar and give permissions to another person to edit it. You can change the colour on this second calendar to differentiate it easily from your consolidated calendar.
In my case, keeping only one calendar allows me to add new entries much faster. On certain apps, especially those with smart text recognition such as Fantastical, it was daunting to start creating events on your phone and Mac and seeing them appear on different calendars. On Apple's Calendar (iCal) app, new entries are set on the first calendar on the list, requiring you to select the correct one from a drop down list, which you are going to forget to do most of the time. By keeping only "One Calendar" you remove this part of the equation and the app won't ask you where do you want to create an event.