There's only one true way to beat FNAF.
Check left door
Open cams
Close cams
Check right door
Open cams
Close cams
Repeat
And shut the door if Bonnie or Chica is at the door. If you keep the camera on Main Stage, or anywhere where Freddy goes, then he won't move. You don't have to keep the cam on Foxy to slow him, you just have to open cams