I suppose that would work if I had a source to cite. Usually when I have an 'ABT' date, it didn't come from any written information. Most of the time, is based on my own conjecture of when the event happened and that's what I put in the description field. Besides the fact that when printing out an FGS, it is then beside the fact instead of having to plow thru everything else to get to the bottom of the report and find out why I put that date in.
And you're right, except for the fact that it still needs to meet the standards and so far, I haven't found anything in any professional genealogy standards that says my way is wrong. My sources have the correct citations and I have made sure that the information from the documents is somewhere in the file for that person and any others it may be connected to.