Being critical with your own capacity

This post I think only relates to small company where employees are less than 30 ppl or where there're no strict structure applied.
It's about how people responses when they're given task while they're still working on one.

By far, I've seen 3 ways of ppl managing their capacity:

• "Yes man" (or "can do guy")
  This guy will say yes and confidently say I can to all the tasks given to him. Usually this type of guy is a smart guy, able to work everything fast and done as it seems. This guy is willing to sacrifice everything for the sake of finishing all the tasks. One thing I notice though, shortcuts were applied everywhere to get things done. The simple reason for this is there are a lot of tasks in hand, and as quickly as possible he wants to get rid of them all one by one.


• Rational guy
  This type of guy is the rational thinking one, when given a new task he will look at his capacity first and dare to say "I can't" if he's asked to finish the task using the time allocated for other task. Mostly guys with this type are a bit perfectionist, they have their argument that task should be finished in a right way, with few shortcuts (or none if possible).


• Quiet guy
  Given tasks beyond his capacity, he will keep quiet. He will keep on working on the tasks one by one, sadly without minding the time limit he has. The result is this guy will work overtime at most and doesn't meet the schedule. The quality of his work might not matter for him, he will keep on working and someday when he is tired enough, he will resign and start over in other place.

So which type is the best?
I would say a small company only needs 1 or 2 "Yes man" and a lot of "rational guy".
There are times where resources are limited and adding more resource is not the best solution. This is where "Yes man" is very helpful, however having too many "Yes man" won't be good either considering the quality of the work.
A growing company is a company which also learn to realize quality does come with price.

One caution for "rational guy", sometimes he might become too rational that he start to reject the task for the sake of task dislike using the current task as an excuse.