I actually don't use stairwell staircases, in office buildings where I work.

I had the freaky experience in a 3 level historic courthouse where I used to work, where I did take the stairs ....but got locked out for at least half an hr. in a stairwell. Thankfully another employee was using the stairs....

I don't want to get into the complicated description but suffice to say at that time I was part of staff who worked for judges and hence, there were all sorts of building security features in place --some good, some not so good.

So from that experience, I just tend not to use the stairwell case in our building. There are some cross over floors which lock out some of exit/entrances.