How does your organization actually track grant deadlines?

I have some questions? how very small nonprofits keep track of grant deadlines and reporting requirements.

Do you use Excel, Airtable, Asana, calendars, or something else?

What happens when one person is managing multiple grants?

Have you ever found a system that actually works well long term?

I'm asking because I've noticed a lot of organizations seem to build their own process rather than use dedicated grant software.