If I apply local group policy for the first time why it is not taking effect untill I restart the machine?

I applied local group policy but policy is not taking effect. I tried this on domain member(machine is in connection with Domain Controller) and on workgroup machine also. I used gpupdate, gpupdate /force, gpupdate /gorce /boot, nothing is working. I can see the rule in rsop.msc also. But policy is not taking effect untill I restart the machine once. After policy got applied if I modify anything or add other rule they take effect immediately, Why is that so ? Can I apply local group policy without restarting ?