I actually think it is not too bad a design, because seconds are the SI base unit for time. Putting something like "x days" requires additional parsing steps and therefore complexity in the implementation. Either knowing or calculating how many seconds there are in a day can be expected of anyone touching a project or configuration at this level of detail.
> seconds are the SI base unit for time
True. But seconds are not the base unit for package compromises coming to light. The appropriate unit for that is almost certainly days.
that kind of complexity is always worth it. Every single time. It's user time that you're saving and it also makes config clearer for readers and cuts out on "too many/little zeroes on accident" errors
It's just library for handling time that 98% of the time your app will be using for something else.
Seconds are also unambiguous. Depending on your chosen definition, "X days" may or may not be influenced by leap seconds and DST changes.
I doubt anyone cares about an hour more or less in this context. But if you want multiple implementations to agree talking about seconds on a monotonic timer is a lot simpler