Not giving an answer to the question in any way .. but, for side info, the certification standards require drop down masks for aircraft which cruise above F250. Below, things are a bit more step A, what did we miss ?, step B, step C and the descent can be a little more leisurely due to the better TOC .. not suggesting that one should dilly dally at all but there is rational time available, after going onto oxygen, to check for finger trouble and so forth.
Talking F160, I think, at levels in the mid-teens, one can invoke a little more deliberation than would be appropriate at F400 or so.
Keeping in mind that any emergency descent involves potential risks with other traffic.