I live in a metric part of the world and use millimeters as my main measuring unit, including type, strokes, and raster effects.

Since inch a s SI unit, it now equals exactly 2.54mm.
For me it means 254ppi is 100ppcm, 127ppi is 50ppcm, and instead of 300ppi I use 120ppcm (equals 304.8ppi) — which gives me exact integer dimensions for all of images I use. The grid becomes meaningful and all objects behave and befriend each other.

Unfortunately for me, Illustrator plays this game not as good as I want it to — I can’t enter 304.8 to Resolution field of Document Raster Effects Settings — Ai rounds it down to 304.

Funny thing is I CAN Rasterize with 304.8ppi set alright... but not Export, because Ai then round it up to 305ppi.

Veeery consistent.
Photoshop by the way allows to use PPCM in Preferences.