Have you ever worked for an “over appreciative” boss that uses thank you, great job, awesome job etc. in abundance. If you have you will understand where I am coming from.
When we put ourselves on the line for someone else then a heartfelt thank you is in order; when we deliver a piece of work that is truly impressive because of its superior quality, the efficiency with which it was carried out or some other measurable factor then a "great job" would be appreciated...getting recognized in these cases is necessary, it makes us feel good, it motivates us to do it again, it works.
On the other hand, if you thank me for simply doing my job and praise my average work as awesome it does not work. Most likely the insincerity of your “thankfulness” will be obvious and that will not help, your praise will be meaningless and your “troops” will think of you as a manipulative person; they will start despising you. In the rare cases when you may be so good an actor that you come across as sincerely appreciative the “troops” will consider you an incompetent dummy that has no clue what a good job is and what the responsibilities and duties of the troops are and you will inadvertently cultivate a culture of mediocrity.
So, to all you bosses out there, do yourself and your organization a favor and don't thank me when I am simply doing my job! I am not doing it for you, I am doing it for me; I am doing it because I want to keep my job... don't ever say thank you because you think that is your job to do, only say it when you really mean it! Don’t praise my work because its your job to do that, only praise my work if you truly believe its outstanding. Most of the time let me do my job and you do yours and we don’t need to thank each other; that’s ok, it works.
From the practical point of view however, things are not as clear cut as I am presenting them to be – people are all different and a good boss will need to consider those differences. An inexperienced employee who lacks confidence may need constant re-assurance that he is doing a good job; an emotionally un-stable individual may need re-assurance that the boss is not out to get him; yet another, just wants to be left alone; and so on, and so on… it is not easy to be a boss; people are all different, they come from different cultural backgrounds, they have received widely varied educations, different experiences have shaped them; in short, they all “speak a different language” and managing a group of them effectively is a delicate balancing act.