It seems that MacOS 15.0 does not respect altered timestamp_timeout values.
Trying to find out why, and how it might be fixable I found nothing. Instead the ability to do sudo via touch ID came to light. Looking for
/etc/pam.d/sudo_local.template
will get you details. I tried for 5 minutes. And it is nonsense!
You work in a terminal, a sudo is needed. With this config enabled, a popup shows up, you have to reach for the mouse, give the window focus, and then do touch id. Typing a password every three days is SO much quicker.