Not so often. Looks like 9 cases of AMZN in the last year compared to over 3000 for Amazon.

Incidentally, abbreviations are not a good way to work around HN's title limit. The idea is to find a shorter meaningful title, not to use tricks to squeeze more in. This is nearly always possible.

Yes, that was my only reason for employing the abbreviation. In any case, it appears that the mods have chosen to switch out the title with a different one (my original carried an excerpt from the job posting which is now removed).