@CarlosR what value(s) do you want to retrieve more often than every 250ms?
In expressions, the "live" gcode values are used, although some live values are themselves only updated periodically, e.g. machine position and sensor temperatures.
We are looking at adding a facility to make selected variables available more often. This will be a major change, requiring the values to be pushed from RRF to an attached SBC or other device, so it wont be in 3.6.0 stable.