As I was drafting my Priority #2 Problem post I could hear readers in my ear saying “You need the Eisenhower matrix – divide work into urgent/not-urgent and important/not-important.” So, a footnote, the problem with the matrix…

While undoubtedly useful for Priority #1 problems – those which are clearly important and/or urgent – the Eisenhower matrix has, at least, three issues in this context.
Firstly, the matrix is binary: things are either urgent or not urgent, and important or not important. Life is seldom that simple. There are usually grey areas: is this urgent? or can it wait?
Then when all the urgent and important things are done and taken away how do you decide between the not-quite-so-important and not-quite-so-urgent? Or maybe between the, “might be urgent” and “might be important” and the “soon to be urgent” and “someone else thinks this is important?”
The search to determine which of several possible work items is the most important and/or urgent itself becomes a costly diversion. Priorities #2s are not so important or urgent that they must be done NOW but benefits are lost when left undone (remember time-value profiles). When working alone you can’t delegate them, and even if you can the effort and/or coordination to delegate them is more than actually doing them.
Second, the Eisenhower matrix has no concept of time. It is a matrix for making decisions were decisions are made and you move on. When there is work to do then making the decision is the first step. Once the decision is made to do something there is real work be done.
That means that doing one thing precludes the others: having made a decision to do A other items, B, C and D, must wait, so each decision carries an opportunity cost. Doing A means not doing B, C and D – or at least not doing them right away.
Plus, the time spent doing A means there is time for doubt (“maybe B was really more important?”) and change (“Emergency – we need C”).
Again, this problem is particularly acute when solo-working although you see it in organisations too. The longer it takes to do work the more time there is to doubt to enter the picture, and the more time for some risk to materialise.
Finally, one problem which doesn’t happen do much when you work solo: what is urgent and what is important are subjective.
In an organisational setting one person may think project A is important while another thinks B is more important than A and third thinks C should be the priority. Finding time for these three people to meet and agree retracts from doing.
Costs of the Priority #2 problem
First is the cost of omission: valuable things don’t get done because more valuable things crowd them out.
Second is the cost of carry: the multitude of should be done wears us down. Individually this manifests itself as cognitive load, your brain knows something needs to be done but you can’t do it. Organisationally it complicates decision making. In both cases it leads to more work and delays trying to decide between priority 2s
Third is the cost of delay: when these things do get done they are less valuable than they would have been if done earlier because the benefits are delayed.
An arbitrary, random, choice between options can be the best decision because it saves time and costs of rational decision making.
Searching for the best option is a fools errand: far better to set a bar and accept everything that passes it. Then optimise the doing rather than argnonise about the best thing to do.
Motivation to do work can be more important than rational decision making. (If you do the one you really want to do first then you will break the deadlock, deliver some value and be ready for the next sooner.)
Be prepared to go into debt to do these things: if you only do what you can afford (money or time) then these things will never get done, their benefits will never get realised and the world will not advance. So if they can meet a hurdle rate, if they makes sense to do, then don’t be worried about borrowing money (or someone else’s time) to get them done.