Yes, I know.
In the violent death section, Valens obviously favours the pre-natal lunation and the Fortune/8th sign technique, but if we cast the charts he gives as examples, the 40th day of the Moon in all but two of them (out of eleven given) either have the 40th day Moon with, opposed or square malefics, I don't think this is a coincidence. Valens is not an easy read (deliberately so as you know) and just like Abu Ma'shar he has placed hints to techniques in other places or in his example charts without explicitly stating "this is what I mean!!", I guess he felt it is up to the reader to figure it out. I don't think we can say "well Valens was a compiler so because I don't understand this technqiue, he must only be reporting it", we have to look at what he was saying but also what he was showing when we examine his examples.
I think it is fair to say he tested this technique and that he found it useful, and if he didn't, his own example charts show him to be in error there.