I do the same and I bang my ball rapidly by stroking my cock, oh guy it is so good to bang the balls with each stroke.
I think it's harder to finish standing up but I've done it plenty of times. Oddly enough, it's easier (but not totally easy) getting a blowjob and climaxing while you're standing than it is to just masturbate in that same position. End result is nearly the same although I certainly would rather have someone catching it all for me.
For me standing in the shower ranks high. I get the water hot right on the penis as I'm getting hard. I use conditioner shampoo as a lube, turn backwards to the water flow and let it run down my ass. In one of our bathrooms I can open the shower door and watch the show in a mirror. Always makes for a big knee weakening climax.
Can't think of any approach that would be different sittling/laying vs. standing. Maybe it's a mental block? I do know some people have a hard time finishing if they have to concentrate on keeping themselves upright, even just kneeling.
For me, masturbating standing up, takes way longer to cum. So I prefer to sit or lay down. Sometimes while showering I cum easily, but that is very rare.
Masturbate standing up watching in a wall mirrow, , with one hand leaning against the wall for support, otherwise I would probably fall over when cuming,
I do it quite often. If I step outside in the garage for a quickie, or if like at work I step into the stall and stand. If its been a long session and I find myself softening up Ill stand and it fixes that right up.