It should but each texture asset has settings that can affect or prevent this, like the MinLODSize, MipBias or TextureGroup it belongs to. There’s also a check to NeverStream a texture which will always keep it in memory, regardless of how far it is from you.
I’d recommend building your streaming data from time to time as you work, to ensure the Mip computations are kept up-to-date. Then you could more carefully check the settings of each texture used by your most expensive materials against this glossary to find any funky settings that might’ve been overlooked during import.