It really comes down to the individual doing the brazing or preparing the frames for robotic brazing.
Most notably, Peugeot proudly advertised on their frames with decals saying "hand brazed" in the 80's, the problem was, a lot of their frames had very sloppy brazing and lug preparation. It took me two trips to the Peugeot dealership to find a PSV bike that had good frame quality. Many had lugs that seemed to have been slighly misaligned to the tubes, gaps between the lugs and tubes, lugs that had points that looked chipped (ground off too much?) off at the tip, blobby brazing coming out of the lugs. I think a lot of french frame builders use their experience at the Peugeot factory as a start to their careers in the business and move on, so there was always a good supply of newby braziers at the Peugeot factories, from hwat I saw with the bikes at the dealerships.
Just glad to have found my PSV with a good frame. Must have been a senior brazier that stayed on at Peugeot.....til the robot welders/braziers came in???

Chombi

I used to get sucked in my big names and top of the line models. Not so anymore. However, with what I have learned about quality road bicycles, I published in a feature article on MY "TEN SPEEDS". This page, Determining Bicycle Quality - Contents, is much of what I have learned, about bicycle frames and the quality associated with them, over the years.

Hope this is a help.

I might add that on the weekend, I scored a Bianchi "Premio" for a good price. Look for pictures of the crappy work on this bicycle. There is actually a 1/8" gap on the drive side chain stay to drop joint - truly substandard.

Midway between those two points on the bike-building spectrum were semi-factory methods such as brazing carousels. On the one hand, a guy who does nothing but headlugs all day gets pretty good fast. On the other hand, he also gets bored fast, so there's always some new guy stepping in just when the quality starts to improve. On top of that, the carousel is designed for speed because it's all about reducing labor costs, so if you sneeze or need to pee or cook a tube because you haven't quite gotten it down yet, the frame's on to the next guy, whether you did the job right or not. Of course, you hope quality control catches it, but if you're an Italian family operation trying to go from 200 to 2000 frames a year in a few years, there's a pretty steep learning curve, especially with the pressure to ship bikes. The Old Man may know how to build a great frame, but supervising a larger operation is a whole other kettle of fish. Not everyone is Ugo De Rosa, and even De Rosa made some dogs during periods of expansion and transition. Relatively few, perhaps, but some.