The distinction between serverless startup time and classic cluster provisioning is a good point. If serverless can start almost immediately, a 60-minute idle period can definitely result in unnecessary usage for notebooks that are left open.

I’d be interested to know whether the 60-minute value is mainly a product-design choice for interactive workflows or whether there are technical reasons for keeping the default that high. The observation that an open notebook may remain active even when no cells are running is particularly important from a cost-management perspective.

For teams concerned about unexpected usage, it seems worthwhile to monitor system.billing.usage alongside query history and establish internal guidance for disconnecting idle notebook sessions. A shorter configurable timeout would also give administrators more control over this type of workload.

After spending time investigating usage and billing, something lightweight like rollerballer.io  can be a quick browser break.