I'd water less on the 16th. The allowed depletion is a user set item and should be honored. If someone says don't get below this its best not to go below it. However anywhere in between field capacity and allowed depletion should result in happy healthy plants. Thus on the 16th it could look at the forecast rain and add just enough to not go over the field capacity.
Because any time you go over the field capacity you've wasted water. If you're wasting rain water (which I do here in Oregon often) so be it. But if I paid to put water in and then by virtue of that ended up wasting rain water technically I didn't need to put down as much as I did.