I usually try to keep the orders “in my hand”, as long as they don´t give something that I need.
I only turn in orders that
- Give me people
- Give me Blueprints
- Give permanent boni
On the spot because those scale with the time you use them, so there is no sense in not getting them as soon as possible.
In addition the blueprints might make an appearance in the drawpool as long as they are not claimed, so it is a good thing to claim them before getting one from the pool to prevent to have fewer useful choices.
The rest depends on the situation, but as long as there is nothing I need in the rewards or there is a risk of not beeing able to fulfill it later on the non-permanent conditions, I usually keep them if possible, since higher impatience gives a boost to happiness, and getting points through happiness as early as possible is a good thing.