I charge at C/10 or 1/10th of the capacity for 12 hours or so, and discharge at C/2 or 1/2 the capacity. I discard the battery if I can’t obtain at least 80% of it’s rated capacity. Sometimes it takes a few cycles to get the required capacity but if I can’t get to the 80% minimum after 3 charge/discharge cycles I toss it.
Some NIMH batteries tolerate fast charging at a 1C or 1/2C rate, but not all batteries will.
Here is some great info on batteries:
Red's Battery Clinic