Google Calendar is one of my most-used tools in my business.
I have shareable calendars that I can share with clients (marketing calendars, payment calendars). And I also have ones that I can use just for myself (personal, family, and my own business info).
I use them for everything. For my clients, we have a payments calendar set up so we know when to expect recurring payments. It’s so handy to keep track of what is coming in.
We have marketing calendars, so we can plan strategy for promotions and JV events.
Google Calendar is free, and you can setup unlimited calendars. So there’s no reason not to use it for one thing or another in your business!