How are small agencies managing client websites after launch?

I’m interested in how small web agencies, freelancers and digital businesses manage client websites after the initial build is finished.

The website build itself is usually fairly well organised as a project, but the ongoing side can end up spread across a lot of places:

• project management tools
• shared inboxes
• spreadsheets
• uptime monitoring
• password managers
• billing/accounting systems
• Slack/Teams
• client notes in documents or emails

For anyone managing multiple client websites, how do you keep track of things like support requests, renewals, hosting/domain reminders, uptime issues, client notes, maintenance agreements and ad hoc work?

Do you prefer using separate specialist tools for each area, or have you found that a more centralised setup works better?

I’m mainly interested in whether centralising this actually saves admin time, or whether it just becomes another system to manage.