On my computers, they are updated when I remember to run the package manager's update command, so that might happen once a week to once a month. On my phone, I tend to quickly install updates when LineageOS sends me a notification that there is one available, since it just takes pressing the download button, then the install button, then waiting, then rebooting whenever i'm ready for it, and you still get to use the phone as long as you want before rebooting without any trouble. It however doesn't let me do that with major versions, and there has been a new one recently, so I'll be updating over ADB…… someday…………