I bleed my brakes yearly, on a summer day with low humidity. I've never cycled the ABS system because I do not have the scan tool (or whatever) needed to do so.
However, both prior to and after bleeding the brakes, I purposely induce wheel lock on an individual wheel basis in order to cycle the ABS system.
This can be done using a variety of techniques. One is to find a safe area and drive into a hard turn while stabbing the brake pedal. This will cycle the ABS for each front wheel, depending on the direction of the turn. I do this in a large parking lot, usually very early in the morning. You don't have to be going fast to do this.
In that same parking lot, make a sharp turning circle until you start to get rear wheelspin. This will cycle the ABS because of the loss of traction. Do this turn in both directions. A warning, sometimes I find this rear wheel spin method induces too much driveline shock to my liking because the ABS system is rapid cycling the brakes on one side while the car is under power. But, so long as you're not giving it lots of power, these negative effects are mitigated. Understand, I'm not talking about a full out powerslide. I'm talking about wheelspin on the inside tire only.
All this said, I am fortunate to have a nearly untraveled road that is under a canopy of trees. Sometimes the edges of the pavement are literally 3 inches deep in leaves. What I do here is get both tires on one side on the leaves and nail the brakes. Instant ABS action on both front and rear wheels on the leaf side. I do this several times for each side of the vehicle. If you have a mechanical limited slip rear diff, this would be the preferred method because inducing inside tire only wheelspin via the parking lot method would be difficult, if not impossible.
Also too, I think "exercising" the ABS system once in a while is a good practice. This is a good way, and reason, to do it.
Lastly, I use Pentosin "Super DOT 4" fluid.
One last thing, I just realized I was on BITOG and not E46Fanatics (a BMW forum). Don't use my parking lot technique on a vehicle with a high center of gravity!!!
FWIW,
Scott