As I said, how long your computer waits on the BIOS screen to wait for a keypress is independent of the OS boot time, and can be set in the BIOS if you need it to be longer. Booting the OS happens after waiting for DEL, and are independent events, one has nothing to do with the other.
So I can have time to press F2 / Del / F8 (go to BIOS / go to OS boot options) and not miss because the window is too narrow.
As I said, how long your computer waits on the BIOS screen to wait for a keypress is independent of the OS boot time, and can be set in the BIOS if you need it to be longer. Booting the OS happens after waiting for DEL, and are independent events, one has nothing to do with the other.
Start playing ball games it will greatly increase your reaction time ;)