Take a look at my windows.....
There is at least a gap of 12mm + each side of the frame which can be as high as 20mm in some places.
They must have used 10 tubes of sealant per window! The sill ares also short - up to an inch away from the brick.
Take a look.....
Houses are completed with no rendering.
Here are the pics;
You can easily see where the sill ends and where they have filled the gaps between the wall and window with a strip of plastic trim .
Another showing the large gap between the end of the frame and the brickwork
Gap shown at the top of the window
Over half inch mastic seal which looks a right bodge
More excessive sealant