If you set everything to Priority 1, you might as well not prioritize at all!

So many times in work and outside it we are dispatching or being dispatched against lists of prioritized tasks.  Sometimes these lists are sequenced in the order they should be done, which makes it pretty clear where to start and where to end (or cut losses if time runs out).

Other times it is a bug list or something where items have been given a priority but no particular order.  In these cases, there are hopefully only a handful of items that are the highest priority, making it still pretty clear to start.

But if a list has almost all items set to the highest priority, this has exactly the same effect as not having prioritized at all-- the person or group working on the list ends up choosing either the items they feel are important (which may follow a totally different agenda to the client/boss/requester), or the ones they feel like working on (often the easiest, or the ones which are funnest to work on).

So, if you are submitting a list of prioritized items, and you want to have some control over when various items get done, make sure you have actually made some hard choices and done real prioritization.  Add more gradation if you want-- perhaps there should be 5 levels of "super-urgent-on-fire-high-priority".  But unless you leave it pretty clear to the person(s) implementing the list, you are giving them the power to decide what should be done.