A few years ago interior designer Laurel Bern did a blog on this practice, i.e, if your walls are a particular color, then painting your trim that exact color.
You can do matte walls and semigloss trim, or not. It's a classic, that people have been doing for literally hundreds of years, but I'm always surprised more don't try it. Super look, serene.

If you're wondering why most of the examples she gives are in many different shades of blue or blue-grayish green, it's because she was answering the question of a reader whose husband wanted blue.

Sheila Bridges did a little twist on this-- went with same color for walls and wainscoting, but contrasting color with the beautiful (stone?) fireplace.

But in this library, walls, woodwork, fireplace, all same color.





Laurel Bern has a strong bent toward traditional, so she shows mostly rooms with very traditional architecture in this paint treatment.
But it can be effective also in rooms that don't necessarily look like they come out of colonial Williamsburg, and are decorated in a more eclectic style:





I still like crisp, contrasting white trim in many applications. We have that in our living room-- white trim with misty, robin's egg walls.
But in our bedroom, which has many doors cutting up the room, including one going to the attic staircase, all one color for everything "calmed" things down and made it more seamless...
Do you like 1) contrasting trim, 2) identical walls and trim, or 3) both, depending on the room or house?