Dwarves will work and complete their tasks, and will take breaks normally after a task is complete and they have a certain desire that needs to be fullfilled (Hunger, Thirst, Tiredness). Once they have fulfill their need, they go back to work if their is a task to do. They may also stop mid way if one of their desires become unfulfilled for too long and starts to become an issues (starving,dehydration, etc.)
My proposed suggestion is to have the ability to set your dwarves labor attitude (how hard and long they will work) to either "Relaxed","Casual","Normal","Over-Worked", or "Slavery".
A Fortress may not be able to use these setting right away. They must wait until they gain a Count or Duke. An Royal Admin will come with the duke for fulfill this role.
The purpose of this will help with tantrum spirals and over all happiness levels. This will also assist with being able to complete tasks faster if they need to be. However the higher a work setting you have, negativity thoughts will be given to your dwarves. However, a lower setting will give happiness thoughts to your dwarves at the price of your fortress work activity being slowed down.
This will also give players the ability to run their fortresses with more control. If you have a really good fortress, then running it on over worked for a period of time can be affordable. However the longer your have this setting on the more accumulative negative thoughts will occur. This may not be an issue however if you have a strong internal guard system in place with your Captain of the Guard.
To give an example of what each setting:
Relaxed: Your dwarves will work if it makes them happy too or not at all, depending on their likes/dislike and beliefs. If they have a need that needs to be fulfilled they are more then likly to drop what they are doing and address it. Dwarves that have a lazy out look on things will more then likly work at a slower pace. Having it on this selection will occur more positive thoughts on your dwarves. Dwarves that have an outlook of a hard working attitude may dislike the way the fortress is currently ran. Examples, Happy thoughts from this mode 35+, negative ones from hard working dwarves only -5
Casual: All your dwarves will work no matter what. In terms of productivity this is a step up for from relaxed, however your dwarves will less likly drop their tasks and address basic needs unless its lingered for too long (about half the length to go from just being hungry to starving.) Majority of your dwarves will gain a small increase in happy thoughts. Example, Happy thoughts gained from this mode about +10.
Normal: Currently how DF handles work at the moment, however they will more then likly actually reach their beds before falling asleep.
OVer Worked: All your dwarves productivity is increased with a sacrifice with some happy thoughts. Lazy dwarves will more then likly have more of an issue with this mode (-10) while hard working dwarves may see an increase from this (+10). Dwarves will eat and drink when need be they need too, however if they drop their tasks to fulfill their needs they may be punished. These negative thoughts will become worse and worse as time goes on, with fight outbreaks likly to occur. Captain of the Guard recommended.
Slavery: Your dwarves are pushed to the max and no one likes it. To keep this mode going you need to have a strong Internal Guard system otherwise your dwarves will lash out. Your fortress productive will be really high and dwarves will move faster here as well. You must take more care with what you have your fortress doing because on Slavery mode dwarves that stop to work are punished with at least prison time or a hammering. This mode is for !!FUN!!!.
Slave Labor: You