Of course it's true in the case of sqlite. It's one of the most used pieces of software ever, and user cpu time spent is going to dwarf any developer time.

Your example should instead be:

- 5 hours of developer time to run in 4 seconds * n

- 5 minutes of developer time to run in 5 seconds * n

As long as n <= 17,700, then the developer time is "not worthwhile." This assumes that you value user time as much as developer time.

In the case of sqlite, the user time may as well be infinite for determining that side of the equation. It's just that widely used.