The edition I have is a 2002 reprint of the original 1978 book. Ian Hogg has written so many books that making sure we are talking about the same one is a little hard
Amazon.com: British American Artillery: WWII-Hardbound (9781853674785): Ian Hogg: Books
By the start of WW II the art/science of gun making was pretty well known. The only real 'stinkers' were going to come from trying to meet unreasonable requirements and/or trying to cobble together something out of bits and pieces that were never intended to go together in the first place.
Every army in WW II would have loved to have had a 105 howitzer that fired to 15,000meters, weighed only 1000kg had 360 traverse and fired 20 rpm. It just wasn't possible. So how far did anybody push the limits of design while still keeping the gun relaible and sturdy enough to tow over hundreds or thousands of miles of bad roads/fields?