On a detached property with a deep garden, distance is the problem. Somebody at the back of the plot is well away from the street, screened by planting, and out of sight of the house. That argues for real resistance on the rear and side openings and for taking the garden gate seriously, because it is the point where being on the property stops being obvious.
On a semi it is the opposite: everything is close, tight and overlooked, and the weakness is geometry rather than distance. The yard is narrow, the wall is shared, and the roofline continues over the next property. What matters there is that the rear door is properly fixed into its frame, that a yard gate cannot be leaned over, and that any opening at first-floor level reachable from an adjoining roof is not simply on a latch.
The racecourse-edge properties get the detached-house treatment regardless of what they are, because that boundary removes the one thing a suburb normally provides. It does not need dramatic spending — a gate that cannot be worked from outside, and a rear door that is actually anchored into masonry, cover most of it. Beyond that, high security locks belong on the specific openings that face the wall and nowhere else.