As far as I am aware, there is nothing that states one way or the other. In all of my experience, I have only seen initials of individuals responsible for the drafting/checking of drawings, and not full names.
This may be due just simply to the limited amount of space in the title block for drafter/checker/engineer/approved initials. Most drawings I have seen do not have enough space to provide full names or even FI, MI, last name formats as looslib has stated.
I can't say that I fully see the benefit or value of adding the full names to the blocks, if it isn't something you're not currently doing. I guess if you have multiple people with the same first, middle, and last initial then it would save a little bit of time trying to decipher who was responsible for the drawing, whereas the full name would tell you immediately who is responsible if there were issues/questions. But how many times do you have that issue? If everyone in the company has always just used initials, it may cause a headache trying to get people to change the habits they have built over years of practice.
I'm curious as to what pros you think having the full name provides?