If you consider the Wikisocion descriptions of rationality and irrationality I think we could almost cut them down to one single question:

How do you cope with stress?

Rationals
(Also called shizotymes in early socionics literature)

1. Tend to plan ahead, make decisions early.
2. Are more often rigid and stubborn.
3. Do not like to change their decisions.
(4. Tend to finish what they started.)
(5. Usually have stiff movements.)
6. Usually more 'authoritarian' leadership style.
7. Low stress tolerance.
These points above all point out what rationals do in order to prevent stress. Planning ahead and finishing decisions gives certainty that whatever they are about to do will work and the chance of getting stressed is minimal. Changing decisions can produce confusion which may leads to stress at the end. Finally, to be able to make this work as they want, they prefer to have a clear hierarchy in their job or other places. If it does become stressful after all, despite all effort, thsi could be a quite annoying situation for a rational.

Irrationals
(Also called cyclotymes in early socionics literature)

1. Tend to wait and see, more spontaneous.
2. Are more often flexible and tolerant.
3. Change their decisions frequently.
(4. Tend to start new things without finishing them.)
(5. Usually have gentle movements.)
6. Usually more 'democratic' leadership style.
7. High stress tolerance.
The irrationals at the other handside is not as much affected by stress as the rational. They don't need to put so much effort in avoiding stress, so they focuses on taking every possibility into account. Decisions don't need to be made early and that's why irrationals can make use of spontaneous changes and are more flexible and adaptable. However, this approach may lead to problems in deciding losing the overview. But if it comes to stress it's not a greater problem for irrationals, since they are somewhat used to it don't perceive it as overly unpleasant.