They need to be held in with nails of some sort so yes it is standard.

When you have something that has a particular level of finish it can be installed using different methods. Using a finish carpenter to whom you've given instructions about how you want the final surface to look, that's possible but not 'standard'. Anything important to you has to be communicated, tracked and inspected. The jamb extensions could be biscuited, and glued.

In the same pic you can clearly see the puttied hole on the window itself, so like the others said, yes, it is standard practice. Some companies won't fill nail holes at all based on it being kind of a "hot button" when it comes to perfection... The only thing I'd question is whether they could have done a little better job, as the touch up paint doesn't look to match that well? ... could just be the pic making it look that way?

At the end of the day, keep in mind that black will show all flaws more than other colors. Ask any auto body technician.

Did you use stained trim around your windows?

we used a color wash actually which was much easier to use than stain.

We uaed a color wash on alder. it was much easier to work with than stain.