It is about fashion. But, big but, fashion often dictates where the money goes. Even though I can see no practical advantage either way, I do agree that most "best work" guns conformed to the fashion. It was pointless to build out-of-fashion guns that would have to be sold at a discount to get rid of them; you may believe that fashionable guns were important at fashionable shoots and that was where the money was. The fact of through lumps does not in and of itself make a gun not a "best work" but is a pointer that most probably the gun did not have the kind of time put into it to make it a "best work" gun. Similar point is flat back SLE's. There are many "best work" flat backs. But after the stocked to the fences style became established as the fashion, future flat backs were graded guns. Ergo, up sprung the myth that a flat back can't possibly be a "best work" gun. Have a look at Boss and Woodward flat back SLE's and tell me a flat back can't be a "best work" gun. The confusion mainly stems, IMO, from the "London style best work" gun. Some say a "best" must be a ALE made in London without through lumps and stocked to the fences. Well, that is the London pattern, so are talking about "best work" guns or London pattern "best work" guns??
DDA