Do you have a problem with comfort or handling that you may believe will be remedied by a shorter stem.
Are you looking for an excuse to buy a shorter stem as shorter stems are more fashionable.
Do you have some money mburning a hole in your pocket and you don’t know what to spend it on.
If you like riding up hills you will find it harder to keep the front wheel on the ground as you weight will be moved rearward and less over your front wheel.
If you like to push up and barrel down hills you may feel your weight is too far forward so would benefit from your weight further back so fit a shorter stem.
You may then feel a little cramped and your steering is more twitchy so adding wider bars, will slow down the steering and stretch your arms a bit so a little less cramped.
If you still feel cramped you will need a frame with a longer effective top tube to allow you have the shorter stem that enables you to push your weight back.
You may not be happy with your current bar width and find a wider bar more comfortable but find your steering slow so shorten your stem to try and speed it up.
The whole relationship between bar lengh, stem lengh and ETT should be tailored to suit fit and performance.
If set up is perfect for fit bit causes the bike to misbehave where and how you ride, its wrong.
If you bike handles every thing you throw at it but you feel it does not fit,then something’s wrong.