Timer settings, when to use a combobox or spinbox?

I was creating a mockup for an login settings window, and when i came to the option for "auto logout", i was wondering if it should be a spinbox, allowing the user to set any value (in minutes), or a combobox with set values (i.e. "Never" / 15 minutes / 30 minutes / 1 hour / 4 hours / etc).

Simplified Mocks:

Option 1

Spinbox

Option 2'

Combobox

Looking for some patterns, i basically came across both options. A few examples from windows:

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Is there any rule for which too use?

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