you need them top and bottom if you use something like that.

problem is you just move the weakpoint from the door to the frame. most frames for garage doors just arent fitted robustly from a security perspective not forgetting often 20 years of wear will have taken its toll on the wood.

remember you will never STOP a thief if they are determined. (well not legally )

BUT you buy yourself time by adding security features.

and you have to make sure the bits you add dont make things worse. Those locks on that black doored garage dont look the best. Youve got no reinforcing plates behind the door so in effect its all reliant on those 2 bolts and very thin garage door steel!!! Also he needs to ensure his garage door frame is properly tied into the brickwork. Think about it, the wood frame would have had some flexibility which to an extent would stop things breaking. now you have taken out the flexibilty putting extra strain on the probably few bolts into the brick! Much better to ensure its properly tied into the brick.