I keep running into this problem over and over when I work in relatively large companies with a matrix management organization.
Basically, I deal with multiple concurrent projects. My "deliverables" are typically monitored by a distinct PM for each project who oversees the project from start to completion. At random times and totally without the input of people who actually do the work, projects are accelerated, throttled, created or canceled.
It happens a lot and this situation leads to two nasty and recurring problems:
I get asked to "estimate" the time for a bunch of deliverables for project X-- with no real distinction between critical high-value tasks and boiler-plate polishing. I do my best and provide estimates which are then recorded into an excel spreadsheet. However, everything subsequently gets thrown into chaos when some other PM declares that project Y is a super hot revenue opportunity requiring every effort to complete on time. That's fine with me and I do my best to prioritize the most important deliverables for both project X and Y-- which invariably means that things get back-burnered if I assess that they're of lesser value compared to other deliverables. Unfortunately, project review for X pops-up while I have my nose to the grindstone and I then have to answer for "past-due" deliverables. It makes me feel like crap because I worked hard to juggle my work so that I meet the most important priorities, but from the point of view of the PM for project X, it is just three "red boxes" on his gantt chart and he doesn't care (and, in fact, holds it against me) if I cleared by desk and worked super-hard to meet a deliverable on hot project Y.
I often need to have collaboration from peers who are working on projects U, V, and W. They're all nice people but they're also "under the gun" of their PM's. Requests for help are too frequently met with silence or tepid responses. By the same token, when I get asked for assistance, I have to struggle very hard to respond in a quality way. Ultimately, we depend on each other for help and the project landscape makes it very hard to predict if/when help can be obtained from peers.
How do you handle this type of situation?
Is this an unavoidable consequence of "Matrix Managment"? Is there anyone other than "the doers" that will even understand if some deliverables have to get sacrificed to meet an important deliverable?
How do I convince disparate stakeholders that sometimes their project has to take a backseat to others for the overall benefit of the mission?