Do you use poweroff or suspend on your Linux systems? Why?
I use Ubuntu btw. Poweroff could use more write cycles on the SSD because it has to read everything at startup, but suspend has to keep supplying power to the RAM
Haven’t needed it to, I guess even after kernel updates you can log off and log back on to set the changes.
Sorry, but to clarify no. When your kernel updates if you just log out and log back in you will still keep the same kernel version because linux keeps running a program on same version until you completely turn the program off.
That's why with the kernel and kernel modules you need to completely restart your system for the kernel to shutdown and use the updated version, it's just the way that linux works.
Hell you can even use a program after uninstalling it until you close it for a year if you wanted to ( once untistalled my termninal emulator, but still had it's window opened so just reinstalled it an hour later after realising I can't spawn a new terminal window )
There is live (kernel) patching which circumvents the need for a restart. But that is meant for servers were you cannot afford the downtime and will only work for a while. Sooner or later you will have to restart to get the latest patches.
Correct me if I’m wrong: sudo user and kernel updates can take effect¿
Not sure what you're trying to ask, are you asking if using sudo to sign in as a different user will make kernel updates take effect? If so, the answer is no.
Linux is an operating system kernel, which basically means it's a program which runs other programs inside of it. For any "normal" program running inside Linux, you can update it by installing the new version and then exiting and relaunching the program so that the installed updates take effect. Similarly, after installing the Linux kernel itself, you have to exit and restart the kernel in order for the update to take effect. Because the kernel runs programs inside of it, exiting the kernel means all of those programs will be exited as well, and because the kernel is the only program running directly on the hardware, exiting the kernel means that your computer will power off. In simpler terms: getting kernel updates to take effect necessarily means you need to exit the old kernel and launch the new one, and there is no way to do that without reboot.