NOT ALL PHILLIPS SCREWDRIVERS ARE THE SAME!! That is because all Phillips screws are not the same. If you experience cam-outs, or find that you are ripping and damaging screwheads, you are probably using a US Phillips screwdriver, when you should be using a JIS-fitting screwdriver.
Did you know that when Henry F. Phillips designed and patented his now famous driver, it was actually designed to cam out? Once too much torque was applied, the Phillips design allowed for the driver to dislodge (or cam-out) by moving "upwardly and outwardly over the walls of the recess."
On the other hand, JIS-fitting drivers are designed not to cam-out easily. This is the reason why JIS-fitting drivers often can be used for both JIS and US Phillips screws, while Phillips drivers can only be used on Phillips screws.
As JIS screws become more popular, the best way to reduce cam-outs and/or ripping out screwheads, is to purchase a JIS-fitting driver.
**Information on this page related to the Phillips design was obtained from U.S. Patents 2,046,343 and 2,046,837.