Well, the old sva bikes didnt have one, you just had to hold the revs a little whilst it warmed up. Ducati dont use one on their 916/748 models....they have a secret little button on the throttle twist grip, that manually holds the butterflies open a touch for a fast idle.
On a project I'm building, that a few of you have seen, Ive ditched the idle control valve and fitted a Ducati throttle. Touché used to block up the control valves pipe and reset the base idle via the stop screw. You'd also need to reset the tps if doing this. Its only job is to provide a fast idle during warm up and to control idle during various loads. I cant really recommend its removed, as you then need to alter the adjustment screw thats set by Jenvy with a big "do not adjust" warning given by them...but I did