I have a rough theory of optimal stopping for decision making.
The first observation is that, given a difficult choice, you of course should do as much research on the topic as possible, use rational principles that underpin philosophy (to value human consciousness and life above all), and try to find the best solution for those you're responsible for.
This plan of study may be better explained by a political scientist or philosopher, but some heuristics I can think of are looking for prior art, studying the underlying political and economical theory, and studying ethical philosophy.
I think the question can be phrased as: How to understand when we've reached a good enough solution? This is an economic problem (related to 'optimal stopping').
A theoretical solution is surprisingly simple.
Obviously research has a generalized 'cost': the more time you spend on research (or say, an idle or passive activity), the less you are furthering your goals through actions. If your decision is time-critical, that is, if the more you delay it the greater the harm, or the lesser benefit accrued, then you may be able to estimate this cost.
The research also has a benefit, or 'utility': the more time you spend on research, the better hopefully will be your decision. In economic terms this may be called a marginal utility.
The solution then is to choose a time when the marginal 'utility' gained by research minus the marginal 'cost' lost by it is maximal, i.e. when you gain the most in terms of achieving your goals.
You can harness your intuition and ask "In the period of X months, how much do I expect to have learned about the issue? How much will that improve my decision? What do I (in terms of objective) lose from delaying until then?"
(1) Self-Historical analysis:
If you've been studying for a decision for T time (1 day, 1 month, etc.), how much has your decision improved compared to lost opportunity?
If you feel it has improved significantly, continue studying.
That said, I would not say this is an exhaustive analysis of decision making of course, and really there isn't one. I would advise a cross-disciplinary approach for long term study. Other important considerations are risk analysis from financial theory, as well as the field of game theory and strategy. The modern Rationalism community condenses some of those topics quite well.