Lock Screen: Custom timing?

(iMac 27" 2019/Ventura 13.4.1)

The lock screen choices for requiring a password after the display is turned off goes: “After 1 minute, After 5 minutes, After 15 minutes, After 1 hour…” wait, whut?

15 minutes is too short for my purposes, and an hour is too long. Anyone know of a way to customize the lock screen timing?

(and an additional mystery: when I went to check the lock screen settings after installing Ventura in the hopes that Apple had included more options, the lock screen timing was set to “13 minutes (custom)”! I have no idea where that setting came from, and when I set it to “After 15 minutes” the “13 minutes (custom)” disappeared from the menu) Body