This is something I've encountered at nearly all jobs. First a little about me, and then the scenario, and finally the question:

I'm a senior level professional (30 years in a professional career). Unlike most coworkers I've had who seem to need to be chased into a corner to find out if they've finished a task, I've always been super on top of things and keep my manager appraised of the status of things, and I never miss deadlines. Even in my new job (started in November), I now have a reputation as being "Miss Organized".

The scenario I keep running into is that we'll all be doing our work as normal, when something hot pops up. A higher manager will send word down the chain that this new task is top priority. My manager tells me so, and I jump on it. It has a due date, say, two months from now, and I need to get my deliverable done in a few days so that the rest of the team gets done in time. In this scenario, the hot task always involves a third party, either an external client or vendor, some kind of collaboration with them. They may or may not see it as top priority like we do, but even if they do they seem to move more slowly than we do. So I reach out to them for the information I need, they give me a few bits of info, so I reply back to probe for more... etc. So nobody's sitting holding the ball, things might be moving a little more slowly than we like but they're moving.

But my manager pings me every two hours for a status, reminds me to reach out to the third party (as if I haven't been which she knows as I copied her on it), asks if we're done yet, what's the hold up, have you tried X, please reach out to the third party again (as if I haven't which she knows as I copied her on that too), etc....

What causes this frenetic nervousness from the manager that everybody, is dropping the ball when they're kept totally in the loop and can see that things are being done and progressing? It feels like they expect a several-week task to be done in a couple hours and are freaking out when it's not. Also, do they really expect me to be able to beat up the third party and make them work faster?