Are the thermal insulating jackets available for Fridges a marketing gimmick or I wonder do they really reduce the cycling time of the compressors?

Keeping the fridge cool and well ventilated should in theory help reduce the compressors workload....but in my mind the storage compartment of the fridge in usually quite well insulated and therefore may not have much infuence on the outter cabinet temperature.

Thoughts?

I have a protective/thermal Jacket for my 40lt Engal, but I bought it to protect the fridge from scratches etc.

Thx.

S.