Gap under Windows?

Frank99

My brother decided to get his back windows done after the company did such a good job of his front windows!
His back windows are above a conservatory and so access to the exterior was very difficult. Although he is not bothered i noticed underneath the shelf on the outside instead of using caulk they use mortar and the gap was about an inch or maybe more and the finish scruffy under the shelf, it seemed to me as if they might not of measured the windows correctly as the neighbours under window shelf seems to sit on the brick with a thin layer of caulk and my brothers almost looks like the window is wearing lipstick under the shelf with the inch or more layer of cement.
They came back and smoothed it off making it look better and they told him that because of the access problem they used a packing method instead which might be upvc tech jargon. He has now used a brick coloured paint to match his original house brick which has all but disguised the mortar as if there was no gap and it is really effective making any photo useless but i am just curious about any guidance on gaps under upvc window ledges on the outside, they are with certass so i could ask them i suppose although he does have his 10 year insurance guarantee and certass certificate in case of any problems.
Anybody have knowledge on the subject of upvc window fitting and is their a rule on how large a gap should be under the outside shelf?