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You are only trying to treat the room at the listening position, you will not be able to treat a domestic space at every position. If you build a studio space from a blank slate you can widen the neutral spot but it's still unlikely to be flat throughout the room.
Excuse a pretty basic question; I understand that you're optimising for a specific point in the room, but does it also generally improve the room, albeit to a lesser extent, or is it actually unlikely to change much outside that spot because you're dealing with reflections from different walls etc etc etc
branwen-
Bass waves move around the walls like water across a surface, they pile up in corners, especially in corners with floors. I have a pretty neutral listening position but there's an extra 6db of bass in the corner of the room behind the listening position. Room modes are often caused by the room length combining with a particular wavelength (50hz is 6.84m) so it reflects on the back wall and returns to mess with the outgoing wave adding and subtracting depending on the length of the room. This is why 50hz bumps are so predictable and difficult to cure in London sized rooms.
In short to answer your question, it doesn't improve the rest of the room much. High frequency reflection attenuation tends to improve the whole room but you are probably only going to get a small sweet spot overall, especially in a small room.
Airhead
You can use REQ to create a convolution IR from a frequency sweep. I've done it for 2 rooms and use Roons IR function to adjust the sound to that room. It's the best sound at the listening point that I've had so far.
If you don't have the mic yet you can use a db level meter on your phone to see where the loud spots in the sweep are. REW can also calculate based on room size and speaker position what your room modes are. You are unlikely to be able to treat them with only bass traps.
Definitely you will have improved the situation by having dense material on the shelves behind the listening position.
You are only trying to treat the room at the listening position, you will not be able to treat a domestic space at every position. If you build a studio space from a blank slate you can widen the neutral spot but it's still unlikely to be flat throughout the room.