Minimum 2.5inch Screws for every Strike
It's crazy how often I'm rekeying a lock and I check to see if the striker plate screws are adequate length and the are these little 3/4" screws that don't even make it through the door frame. They are definitely helping a little bit, but oh man, with a screwdriver and some longer screws, we can bump up the security against kicking or bashing by probably 2000%! Seriously, so you'd have to kick 20× harder to break it in. Those strike plate screws need to go all the way through the door frame, and deep into the 2×4 behind it. Typically 2.5inch screws will do the trick. They need to be in every single strike plate on all of your doors. That means the only way the door will open if they can get that entire 2×4 to break with the door frame, and that will make the biggest, strongest men kick it over and over to get it to break.
And If you're afraid of the police or military breaking down your door by 4 big dudes with one of those battering ram things? You can upgrade to a jumbo sizes strike plate that will require that 2×4 to be completely taken out. They will be better off cutting a hole in the door or driving a car through the wall!