It seems that different people have different techniques, but I read somewhere that the recommended method was to activate the ramp and then push the wagon you require uncoupled over it until the couplers disengage, then you reverse the loco and pull away from the wagon(s) you've uncoupled. This means you have to leave the coupler activated for the duration of the process, so having a short pulse is no good for this method.

The instructions I remember from decades ago indicated you should operate the uncoupler as you push the car over it. Then you may continue to push the car(s) to whatever place you want them left. So you should push the cars over the uncoupler not pull them over the uncoupler. The pre-uncouplers prevent the couplers from re-engaging and you can then continue to push the cars to the location you wish to leave them. When operated like this, you need far fewer uncouplers on your layout.

Some lighter coaches or cars may actually be lifted off the rails by the uncoupler. For example, an unloaded Eaos hopper car may not have sufficient weight to remain on the rails if the uncoupler passes under the bogie.
I find that it is best to activate the uncoupler while the car in question is over it. It is supposed to open the coupler and still permit the car to be pushed without the coupler re-engaging.
I have not used the uncoupler for K or C track so I cannot comment on the operation of those.
You also might want to take care to ensure that the half length uncoupler section is placed between straight sections, so that the coupler is not off-centre at all when passing over the uncoupler. This ensures that the device will operate properly.
Loks, cars and coaches equipped with the 7203 close coupler require inspection to ensure that the folded part of the coupler that extends underneath is properly aligned and not bent, so that it can be released as required by the uncoupler.

Regards

Mike C