Is this a theoretical question or a fact?
Mostly depends on speaker design, their size, how far they are apart, your listening distance and placing in room.
If you want a hot presentation (more high frequency energy) choose good toe in and if you want coherency on a wider area decrease it.
Keep in mind that toe in alters high frequency response, the level of side walls reflection, and the relationship of direct and early reflected sounds.
Only experimentation can give you the best coherency considering also what kind of tonality your speaker has and how wide you want your sweet spot.
