I believe in theory that you should be able to make all of your 16 selections and it should play them in the order that they were selected including any repeat selections of the same track.
However theory is not always what happens in reality! I have found that they tend to get a bit hit and miss when more than three or four selections a made, mine will sometimes play six selections with no problems & sometimes miss one when three have been selected.
My experience has been similar to Scudie’s. I think it may be more likely to miss songs if the selections are made rapidly but haven’t tested that theory because I don’t really have the patience.