Installation of interior window sill, especially in drywall construction

Hello everyone,

I have questions about interior window sills specifically in drywall construction:

1.) How are interior window sills installed in drywall construction? With foam?
2.) Are there technical reasons why interior window sills are mostly installed according to the left variant in the sketch? At least that's what I've seen as a layperson. It probably comes from "regular" plastering because plastering is done only after the window sill is installed.
3.) Or is drywall construction completely flexible and you do it according to taste? Does anyone have pictures of the right variant?

Thank you very much

1.
There is special window sill mortar for granite or stone window sills.

Wood is glued or screwed.

2 and 3.
For simplicity, when plastering, if the window is 120 cm wide, you also get a 120 cm window sill. Then it is plastered, and depending on the window frame width, 1 to 3 cm of plaster is applied on each side, so you have this built-in window sill. Otherwise, it must be clear beforehand how far the plastering will go.

With drywall construction, the window sill is simply glued between the drywall walls; accordingly, there is no overhang. Realizing this with an overhang in drywall would be too complex.

Since I received a message from an admin that images from external servers are not allowed, here uploaded directly again. Unfortunately, there was an error message in the preview during the last attempt.

Does anyone happen to have pictures of the different installation variants, especially in drywall construction or from a prefabricated house?